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Drop various unused #include statements. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Joanne Koong <joannelkoong@gmail.com> Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Add inode and wpc fields to pass the inode and writeback context that are needed in the entire writeback call chain, and let the callers initialize all fields in the writeback context before calling iomap_writepages to simplify the argument passing. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Joanne Koong <joannelkoong@gmail.com> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
…blocks We don't care about the count of outstanding ioends, just if there is one. Replace the count variable passed to iomap_writepage_map_blocks with a boolean to make that more clear. Signed-off-by: Joanne Koong <joannelkoong@gmail.com> [hch: rename the variable, update the commit message] Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
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Without the change `perf `hangs up on charaster devices. On my system
it's enough to run system-wide sampler for a few seconds to get the
hangup:
$ perf record -a -g --call-graph=dwarf
$ perf report
# hung
`strace` shows that hangup happens on reading on a character device
`/dev/dri/renderD128`
$ strace -y -f -p 2780484
strace: Process 2780484 attached
pread64(101</dev/dri/renderD128>, strace: Process 2780484 detached
It's call trace descends into `elfutils`:
$ gdb -p 2780484
(gdb) bt
#0 0x00007f5e508f04b7 in __libc_pread64 (fd=101, buf=0x7fff9df7edb0, count=0, offset=0)
at ../sysdeps/unix/sysv/linux/pread64.c:25
#1 0x00007f5e52b79515 in read_file () from /<<NIX>>/elfutils-0.192/lib/libelf.so.1
#2 0x00007f5e52b25666 in libdw_open_elf () from /<<NIX>>/elfutils-0.192/lib/libdw.so.1
#3 0x00007f5e52b25907 in __libdw_open_file () from /<<NIX>>/elfutils-0.192/lib/libdw.so.1
#4 0x00007f5e52b120a9 in dwfl_report_elf@@ELFUTILS_0.156 ()
from /<<NIX>>/elfutils-0.192/lib/libdw.so.1
#5 0x000000000068bf20 in __report_module (al=al@entry=0x7fff9df80010, ip=ip@entry=139803237033216, ui=ui@entry=0x5369b5e0)
at util/dso.h:537
#6 0x000000000068c3d1 in report_module (ip=139803237033216, ui=0x5369b5e0) at util/unwind-libdw.c:114
#7 frame_callback (state=0x535aef10, arg=0x5369b5e0) at util/unwind-libdw.c:242
#8 0x00007f5e52b261d3 in dwfl_thread_getframes () from /<<NIX>>/elfutils-0.192/lib/libdw.so.1
#9 0x00007f5e52b25bdb in get_one_thread_cb () from /<<NIX>>/elfutils-0.192/lib/libdw.so.1
#10 0x00007f5e52b25faa in dwfl_getthreads () from /<<NIX>>/elfutils-0.192/lib/libdw.so.1
#11 0x00007f5e52b26514 in dwfl_getthread_frames () from /<<NIX>>/elfutils-0.192/lib/libdw.so.1
#12 0x000000000068c6ce in unwind__get_entries (cb=cb@entry=0x5d4620 <unwind_entry>, arg=arg@entry=0x10cd5fa0,
thread=thread@entry=0x1076a290, data=data@entry=0x7fff9df80540, max_stack=max_stack@entry=127,
best_effort=best_effort@entry=false) at util/thread.h:152
#13 0x00000000005dae95 in thread__resolve_callchain_unwind (evsel=0x106006d0, thread=0x1076a290, cursor=0x10cd5fa0,
sample=0x7fff9df80540, max_stack=127, symbols=true) at util/machine.c:2939
#14 thread__resolve_callchain_unwind (thread=0x1076a290, cursor=0x10cd5fa0, evsel=0x106006d0, sample=0x7fff9df80540,
max_stack=127, symbols=true) at util/machine.c:2920
#15 __thread__resolve_callchain (thread=0x1076a290, cursor=0x10cd5fa0, evsel=0x106006d0, evsel@entry=0x7fff9df80440,
sample=0x7fff9df80540, parent=parent@entry=0x7fff9df804a0, root_al=root_al@entry=0x7fff9df80440, max_stack=127, symbols=true)
at util/machine.c:2970
#16 0x00000000005d0cb2 in thread__resolve_callchain (thread=<optimized out>, cursor=<optimized out>, evsel=0x7fff9df80440,
sample=<optimized out>, parent=0x7fff9df804a0, root_al=0x7fff9df80440, max_stack=127) at util/machine.h:198
#17 sample__resolve_callchain (sample=<optimized out>, cursor=<optimized out>, parent=parent@entry=0x7fff9df804a0,
evsel=evsel@entry=0x106006d0, al=al@entry=0x7fff9df80440, max_stack=max_stack@entry=127) at util/callchain.c:1127
#18 0x0000000000617e08 in hist_entry_iter__add (iter=iter@entry=0x7fff9df80480, al=al@entry=0x7fff9df80440, max_stack_depth=127,
arg=arg@entry=0x7fff9df81ae0) at util/hist.c:1255
#19 0x000000000045d2d0 in process_sample_event (tool=0x7fff9df81ae0, event=<optimized out>, sample=0x7fff9df80540,
evsel=0x106006d0, machine=<optimized out>) at builtin-report.c:334
#20 0x00000000005e3bb1 in perf_session__deliver_event (session=0x105ff2c0, event=0x7f5c7d735ca0, tool=0x7fff9df81ae0,
file_offset=2914716832, file_path=0x105ffbf0 "perf.data") at util/session.c:1367
#21 0x00000000005e8d93 in do_flush (oe=0x105ffa50, show_progress=false) at util/ordered-events.c:245
#22 __ordered_events__flush (oe=0x105ffa50, how=OE_FLUSH__ROUND, timestamp=<optimized out>) at util/ordered-events.c:324
#23 0x00000000005e1f64 in perf_session__process_user_event (session=0x105ff2c0, event=0x7f5c7d752b18, file_offset=2914835224,
file_path=0x105ffbf0 "perf.data") at util/session.c:1419
#24 0x00000000005e47c7 in reader__read_event (rd=rd@entry=0x7fff9df81260, session=session@entry=0x105ff2c0,
--Type <RET> for more, q to quit, c to continue without paging--
quit
prog=prog@entry=0x7fff9df81220) at util/session.c:2132
#25 0x00000000005e4b37 in reader__process_events (rd=0x7fff9df81260, session=0x105ff2c0, prog=0x7fff9df81220)
at util/session.c:2181
#26 __perf_session__process_events (session=0x105ff2c0) at util/session.c:2226
#27 perf_session__process_events (session=session@entry=0x105ff2c0) at util/session.c:2390
#28 0x0000000000460add in __cmd_report (rep=0x7fff9df81ae0) at builtin-report.c:1076
#29 cmd_report (argc=<optimized out>, argv=<optimized out>) at builtin-report.c:1827
#30 0x00000000004c5a40 in run_builtin (p=p@entry=0xd8f7f8 <commands+312>, argc=argc@entry=1, argv=argv@entry=0x7fff9df844b0)
at perf.c:351
#31 0x00000000004c5d63 in handle_internal_command (argc=argc@entry=1, argv=argv@entry=0x7fff9df844b0) at perf.c:404
#32 0x0000000000442de3 in run_argv (argcp=<synthetic pointer>, argv=<synthetic pointer>) at perf.c:448
#33 main (argc=<optimized out>, argv=0x7fff9df844b0) at perf.c:556
The hangup happens because nothing in` perf` or `elfutils` checks if a
mapped file is easily readable.
The change conservatively skips all non-regular files.
Signed-off-by: Sergei Trofimovich <slyich@gmail.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/r/20250505174419.2814857-1-slyich@gmail.com
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
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At least one diff in series https://patchwork.kernel.org/project/linux-block/list/?series=980069 irrelevant now for [{'archived': False, 'project': 241}] search patterns |
…l_access() Function copy_from_user() and copy_to_user() may sleep because of page fault, and they cannot be called in spin_lock hold context. Here move function calling of copy_from_user() and copy_to_user() before spinlock context in function kvm_eiointc_ctrl_access(). Otherwise there will be possible warning such as: BUG: sleeping function called from invalid context at include/linux/uaccess.h:192 in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 6292, name: qemu-system-loo preempt_count: 1, expected: 0 RCU nest depth: 0, expected: 0 INFO: lockdep is turned off. irq event stamp: 0 hardirqs last enabled at (0): [<0000000000000000>] 0x0 hardirqs last disabled at (0): [<9000000004c4a554>] copy_process+0x90c/0x1d40 softirqs last enabled at (0): [<9000000004c4a554>] copy_process+0x90c/0x1d40 softirqs last disabled at (0): [<0000000000000000>] 0x0 CPU: 41 UID: 0 PID: 6292 Comm: qemu-system-loo Tainted: G W 6.17.0-rc3+ #31 PREEMPT(full) Tainted: [W]=WARN Stack : 0000000000000076 0000000000000000 9000000004c28264 9000100092ff4000 9000100092ff7b80 9000100092ff7b88 0000000000000000 9000100092ff7cc8 9000100092ff7cc0 9000100092ff7cc0 9000100092ff7a00 0000000000000001 0000000000000001 9000100092ff7b88 947d2f9216a5e8b9 900010008773d880 00000000ffff8b9f fffffffffffffffe 0000000000000ba1 fffffffffffffffe 000000000000003e 900000000825a15b 000010007ad38000 9000100092ff7ec0 0000000000000000 0000000000000000 9000000006f3ac60 9000000007252000 0000000000000000 00007ff746ff2230 0000000000000053 9000200088a021b0 0000555556c9d190 0000000000000000 9000000004c2827c 000055556cfb5f40 00000000000000b0 0000000000000007 0000000000000007 0000000000071c1d Call Trace: [<9000000004c2827c>] show_stack+0x5c/0x180 [<9000000004c20fac>] dump_stack_lvl+0x94/0xe4 [<9000000004c99c7c>] __might_resched+0x26c/0x290 [<9000000004f68968>] __might_fault+0x20/0x88 [<ffff800002311de0>] kvm_eiointc_ctrl_access.isra.0+0x88/0x380 [kvm] [<ffff8000022f8514>] kvm_device_ioctl+0x194/0x290 [kvm] [<900000000506b0d8>] sys_ioctl+0x388/0x1010 [<90000000063ed210>] do_syscall+0xb0/0x2d8 [<9000000004c25ef8>] handle_syscall+0xb8/0x158 Cc: stable@vger.kernel.org Fixes: 1ad7efa ("LoongArch: KVM: Add EIOINTC user mode read and write functions") Signed-off-by: Bibo Mao <maobibo@loongson.cn> Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
…s_access() Function copy_from_user() and copy_to_user() may sleep because of page fault, and they cannot be called in spin_lock hold context. Here move function calling of copy_from_user() and copy_to_user() before spinlock context in function kvm_eiointc_ctrl_access(). Otherwise there will be possible warning such as: BUG: sleeping function called from invalid context at include/linux/uaccess.h:192 in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 6292, name: qemu-system-loo preempt_count: 1, expected: 0 RCU nest depth: 0, expected: 0 INFO: lockdep is turned off. irq event stamp: 0 hardirqs last enabled at (0): [<0000000000000000>] 0x0 hardirqs last disabled at (0): [<9000000004c4a554>] copy_process+0x90c/0x1d40 softirqs last enabled at (0): [<9000000004c4a554>] copy_process+0x90c/0x1d40 softirqs last disabled at (0): [<0000000000000000>] 0x0 CPU: 41 UID: 0 PID: 6292 Comm: qemu-system-loo Tainted: G W 6.17.0-rc3+ #31 PREEMPT(full) Tainted: [W]=WARN Stack : 0000000000000076 0000000000000000 9000000004c28264 9000100092ff4000 9000100092ff7b80 9000100092ff7b88 0000000000000000 9000100092ff7cc8 9000100092ff7cc0 9000100092ff7cc0 9000100092ff7a00 0000000000000001 0000000000000001 9000100092ff7b88 947d2f9216a5e8b9 900010008773d880 00000000ffff8b9f fffffffffffffffe 0000000000000ba1 fffffffffffffffe 000000000000003e 900000000825a15b 000010007ad38000 9000100092ff7ec0 0000000000000000 0000000000000000 9000000006f3ac60 9000000007252000 0000000000000000 00007ff746ff2230 0000000000000053 9000200088a021b0 0000555556c9d190 0000000000000000 9000000004c2827c 000055556cfb5f40 00000000000000b0 0000000000000007 0000000000000007 0000000000071c1d Call Trace: [<9000000004c2827c>] show_stack+0x5c/0x180 [<9000000004c20fac>] dump_stack_lvl+0x94/0xe4 [<9000000004c99c7c>] __might_resched+0x26c/0x290 [<9000000004f68968>] __might_fault+0x20/0x88 [<ffff800002311de0>] kvm_eiointc_regs_access.isra.0+0x88/0x380 [kvm] [<ffff8000022f8514>] kvm_device_ioctl+0x194/0x290 [kvm] [<900000000506b0d8>] sys_ioctl+0x388/0x1010 [<90000000063ed210>] do_syscall+0xb0/0x2d8 [<9000000004c25ef8>] handle_syscall+0xb8/0x158 Cc: stable@vger.kernel.org Fixes: 1ad7efa ("LoongArch: KVM: Add EIOINTC user mode read and write functions") Signed-off-by: Bibo Mao <maobibo@loongson.cn> Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
…status_access() Function copy_from_user() and copy_to_user() may sleep because of page fault, and they cannot be called in spin_lock hold context. Here move funtcion calling of copy_from_user() and copy_to_user() out of function kvm_eiointc_sw_status_access(). Otherwise there will be possible warning such as: BUG: sleeping function called from invalid context at include/linux/uaccess.h:192 in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 6292, name: qemu-system-loo preempt_count: 1, expected: 0 RCU nest depth: 0, expected: 0 INFO: lockdep is turned off. irq event stamp: 0 hardirqs last enabled at (0): [<0000000000000000>] 0x0 hardirqs last disabled at (0): [<9000000004c4a554>] copy_process+0x90c/0x1d40 softirqs last enabled at (0): [<9000000004c4a554>] copy_process+0x90c/0x1d40 softirqs last disabled at (0): [<0000000000000000>] 0x0 CPU: 41 UID: 0 PID: 6292 Comm: qemu-system-loo Tainted: G W 6.17.0-rc3+ #31 PREEMPT(full) Tainted: [W]=WARN Stack : 0000000000000076 0000000000000000 9000000004c28264 9000100092ff4000 9000100092ff7b80 9000100092ff7b88 0000000000000000 9000100092ff7cc8 9000100092ff7cc0 9000100092ff7cc0 9000100092ff7a00 0000000000000001 0000000000000001 9000100092ff7b88 947d2f9216a5e8b9 900010008773d880 00000000ffff8b9f fffffffffffffffe 0000000000000ba1 fffffffffffffffe 000000000000003e 900000000825a15b 000010007ad38000 9000100092ff7ec0 0000000000000000 0000000000000000 9000000006f3ac60 9000000007252000 0000000000000000 00007ff746ff2230 0000000000000053 9000200088a021b0 0000555556c9d190 0000000000000000 9000000004c2827c 000055556cfb5f40 00000000000000b0 0000000000000007 0000000000000007 0000000000071c1d Call Trace: [<9000000004c2827c>] show_stack+0x5c/0x180 [<9000000004c20fac>] dump_stack_lvl+0x94/0xe4 [<9000000004c99c7c>] __might_resched+0x26c/0x290 [<9000000004f68968>] __might_fault+0x20/0x88 [<ffff800002311de0>] kvm_eiointc_sw_status_access.isra.0+0x88/0x380 [kvm] [<ffff8000022f8514>] kvm_device_ioctl+0x194/0x290 [kvm] [<900000000506b0d8>] sys_ioctl+0x388/0x1010 [<90000000063ed210>] do_syscall+0xb0/0x2d8 [<9000000004c25ef8>] handle_syscall+0xb8/0x158 Cc: stable@vger.kernel.org Fixes: 1ad7efa ("LoongArch: KVM: Add EIOINTC user mode read and write functions") Signed-off-by: Bibo Mao <maobibo@loongson.cn> Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
…s_access() Function copy_from_user() and copy_to_user() may sleep because of page fault, and they cannot be called in spin_lock hold context. Here move function calling of copy_from_user() and copy_to_user() out of spinlock context in function kvm_pch_pic_regs_access(). Otherwise there will be possible warning such as: BUG: sleeping function called from invalid context at include/linux/uaccess.h:192 in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 6292, name: qemu-system-loo preempt_count: 1, expected: 0 RCU nest depth: 0, expected: 0 INFO: lockdep is turned off. irq event stamp: 0 hardirqs last enabled at (0): [<0000000000000000>] 0x0 hardirqs last disabled at (0): [<9000000004c4a554>] copy_process+0x90c/0x1d40 softirqs last enabled at (0): [<9000000004c4a554>] copy_process+0x90c/0x1d40 softirqs last disabled at (0): [<0000000000000000>] 0x0 CPU: 41 UID: 0 PID: 6292 Comm: qemu-system-loo Tainted: G W 6.17.0-rc3+ #31 PREEMPT(full) Tainted: [W]=WARN Stack : 0000000000000076 0000000000000000 9000000004c28264 9000100092ff4000 9000100092ff7b80 9000100092ff7b88 0000000000000000 9000100092ff7cc8 9000100092ff7cc0 9000100092ff7cc0 9000100092ff7a00 0000000000000001 0000000000000001 9000100092ff7b88 947d2f9216a5e8b9 900010008773d880 00000000ffff8b9f fffffffffffffffe 0000000000000ba1 fffffffffffffffe 000000000000003e 900000000825a15b 000010007ad38000 9000100092ff7ec0 0000000000000000 0000000000000000 9000000006f3ac60 9000000007252000 0000000000000000 00007ff746ff2230 0000000000000053 9000200088a021b0 0000555556c9d190 0000000000000000 9000000004c2827c 000055556cfb5f40 00000000000000b0 0000000000000007 0000000000000007 0000000000071c1d Call Trace: [<9000000004c2827c>] show_stack+0x5c/0x180 [<9000000004c20fac>] dump_stack_lvl+0x94/0xe4 [<9000000004c99c7c>] __might_resched+0x26c/0x290 [<9000000004f68968>] __might_fault+0x20/0x88 [<ffff800002311de0>] kvm_pch_pic_regs_access.isra.0+0x88/0x380 [kvm] [<ffff8000022f8514>] kvm_device_ioctl+0x194/0x290 [kvm] [<900000000506b0d8>] sys_ioctl+0x388/0x1010 [<90000000063ed210>] do_syscall+0xb0/0x2d8 [<9000000004c25ef8>] handle_syscall+0xb8/0x158 Cc: stable@vger.kernel.org Fixes: d206d95 ("LoongArch: KVM: Add PCHPIC user mode read and write functions") Signed-off-by: Bibo Mao <maobibo@loongson.cn> Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
commit 2a6c727 ("cpufreq: Initialize cpufreq-based frequency-invariance later") postponed the frequency invariance initialization to avoid disabling it in the error case. This isn't locking safe, instead move the initialization up before the subsys interface is registered (which will rebuild the sched_domains) and add the corresponding disable on the error path. Observed lockdep without this patch: [ 0.989686] ====================================================== [ 0.989688] WARNING: possible circular locking dependency detected [ 0.989690] 6.17.0-rc4-cix-build+ #31 Tainted: G S [ 0.989691] ------------------------------------------------------ [ 0.989692] swapper/0/1 is trying to acquire lock: [ 0.989693] ffff800082ada7f8 (sched_energy_mutex){+.+.}-{4:4}, at: rebuild_sched_domains_energy+0x30/0x58 [ 0.989705] but task is already holding lock: [ 0.989706] ffff000088c89bc8 (&policy->rwsem){+.+.}-{4:4}, at: cpufreq_online+0x7f8/0xbe0 [ 0.989713] which lock already depends on the new lock. Fixes: 2a6c727 ("cpufreq: Initialize cpufreq-based frequency-invariance later") Signed-off-by: Christian Loehle <christian.loehle@arm.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
When switching IO schedulers on a block device, blkcg_activate_policy() can race with concurrent blkcg deletion, leading to a use-after-free of the blkg. T1: T2: elv_iosched_store blkg_destroy elevator_switch kill(&blkg->refcnt) // blkg->refcnt=0 ... blkg_release // call_rcu blkcg_activate_policy __blkg_release list for blkg blkg_free blkg_free_workfn ->pd_free_fn(pd) blkg_get(blkg) // blkg->refcnt=0->1 list_del_init(&blkg->q_node) kfree(blkg) blkg_put(pinned_blkg) // blkg->refcnt=1->0 blkg_release // call_rcu again call_rcu(..., __blkg_release) Fix this by replacing blkg_get() with blkg_tryget(), which fails if the blkg's refcount has already reached zero. If blkg_tryget() fails, skip processing this blkg since it's already being destroyed. The uaf call trace is as follows: ================================================================== BUG: KASAN: slab-use-after-free in rcu_accelerate_cbs+0x114/0x120 Read of size 8 at addr ffff88815a20b5d8 by task bash/1068 CPU: 0 PID: 1068 Comm: bash Not tainted 6.6.0-g6918ead378dc-dirty #31 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.1-2.fc37 04/01/2014 Call Trace: <IRQ> rcu_accelerate_cbs+0x114/0x120 rcu_report_qs_rdp+0x1fb/0x3e0 rcu_core+0x4d7/0x6f0 handle_softirqs+0x198/0x550 irq_exit_rcu+0x130/0x190 sysvec_apic_timer_interrupt+0x6e/0x90 </IRQ> <TASK> asm_sysvec_apic_timer_interrupt+0x16/0x20 Allocated by task 1031: kasan_save_stack+0x1c/0x40 kasan_set_track+0x21/0x30 __kasan_kmalloc+0x8b/0x90 blkg_alloc+0xb6/0x9c0 blkg_create+0x8c6/0x1010 blkg_lookup_create+0x2ca/0x660 bio_associate_blkg_from_css+0xfb/0x4e0 bio_associate_blkg+0x62/0xf0 bio_init+0x272/0x8d0 bio_alloc_bioset+0x45a/0x760 ext4_bio_write_folio+0x68e/0x10d0 mpage_submit_folio+0x14a/0x2b0 mpage_process_page_bufs+0x1b1/0x390 mpage_prepare_extent_to_map+0xa91/0x1060 ext4_do_writepages+0x948/0x1c50 ext4_writepages+0x23f/0x4a0 do_writepages+0x162/0x5e0 filemap_fdatawrite_wbc+0x11a/0x180 __filemap_fdatawrite_range+0x9d/0xd0 file_write_and_wait_range+0x91/0x110 ext4_sync_file+0x1c1/0xaa0 __x64_sys_fsync+0x55/0x90 do_syscall_64+0x55/0x100 entry_SYSCALL_64_after_hwframe+0x78/0xe2 Freed by task 24: kasan_save_stack+0x1c/0x40 kasan_set_track+0x21/0x30 kasan_save_free_info+0x27/0x40 __kasan_slab_free+0x106/0x180 __kmem_cache_free+0x162/0x350 process_one_work+0x573/0xd30 worker_thread+0x67f/0xc30 kthread+0x28b/0x350 ret_from_fork+0x30/0x70 ret_from_fork_asm+0x1b/0x30 Fixes: f1c006f ("blk-cgroup: synchronize pd_free_fn() from blkg_free_workfn() and blkcg_deactivate_policy()") Signed-off-by: Zheng Qixing <zhengqixing@huawei.com>
When switching IO schedulers on a block device, blkcg_activate_policy() can race with concurrent blkcg deletion, leading to a use-after-free of the blkg. T1: T2: elv_iosched_store blkg_destroy elevator_switch kill(&blkg->refcnt) // blkg->refcnt=0 ... blkg_release // call_rcu blkcg_activate_policy __blkg_release list for blkg blkg_free blkg_free_workfn ->pd_free_fn(pd) blkg_get(blkg) // blkg->refcnt=0->1 list_del_init(&blkg->q_node) kfree(blkg) blkg_put(pinned_blkg) // blkg->refcnt=1->0 blkg_release // call_rcu again call_rcu(..., __blkg_release) Fix this by replacing blkg_get() with blkg_tryget(), which fails if the blkg's refcount has already reached zero. If blkg_tryget() fails, skip processing this blkg since it's already being destroyed. The uaf call trace is as follows: ================================================================== BUG: KASAN: slab-use-after-free in rcu_accelerate_cbs+0x114/0x120 Read of size 8 at addr ffff88815a20b5d8 by task bash/1068 CPU: 0 PID: 1068 Comm: bash Not tainted 6.6.0-g6918ead378dc-dirty #31 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.1-2.fc37 04/01/2014 Call Trace: <IRQ> rcu_accelerate_cbs+0x114/0x120 rcu_report_qs_rdp+0x1fb/0x3e0 rcu_core+0x4d7/0x6f0 handle_softirqs+0x198/0x550 irq_exit_rcu+0x130/0x190 sysvec_apic_timer_interrupt+0x6e/0x90 </IRQ> <TASK> asm_sysvec_apic_timer_interrupt+0x16/0x20 Allocated by task 1031: kasan_save_stack+0x1c/0x40 kasan_set_track+0x21/0x30 __kasan_kmalloc+0x8b/0x90 blkg_alloc+0xb6/0x9c0 blkg_create+0x8c6/0x1010 blkg_lookup_create+0x2ca/0x660 bio_associate_blkg_from_css+0xfb/0x4e0 bio_associate_blkg+0x62/0xf0 bio_init+0x272/0x8d0 bio_alloc_bioset+0x45a/0x760 ext4_bio_write_folio+0x68e/0x10d0 mpage_submit_folio+0x14a/0x2b0 mpage_process_page_bufs+0x1b1/0x390 mpage_prepare_extent_to_map+0xa91/0x1060 ext4_do_writepages+0x948/0x1c50 ext4_writepages+0x23f/0x4a0 do_writepages+0x162/0x5e0 filemap_fdatawrite_wbc+0x11a/0x180 __filemap_fdatawrite_range+0x9d/0xd0 file_write_and_wait_range+0x91/0x110 ext4_sync_file+0x1c1/0xaa0 __x64_sys_fsync+0x55/0x90 do_syscall_64+0x55/0x100 entry_SYSCALL_64_after_hwframe+0x78/0xe2 Freed by task 24: kasan_save_stack+0x1c/0x40 kasan_set_track+0x21/0x30 kasan_save_free_info+0x27/0x40 __kasan_slab_free+0x106/0x180 __kmem_cache_free+0x162/0x350 process_one_work+0x573/0xd30 worker_thread+0x67f/0xc30 kthread+0x28b/0x350 ret_from_fork+0x30/0x70 ret_from_fork_asm+0x1b/0x30 Fixes: f1c006f ("blk-cgroup: synchronize pd_free_fn() from blkg_free_workfn() and blkcg_deactivate_policy()") Signed-off-by: Zheng Qixing <zhengqixing@huawei.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
Pull request for series with
subject: iomap: header diet
version: 1
url: https://patchwork.kernel.org/project/linux-block/list/?series=980069