Skip to content

Fix bpf_strnstr len error #5852

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Closed
kernel-patches-daemon-bpf-rc wants to merge 2 commits into from
Closed

Fix bpf_strnstr len error #5852

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
db0d677
bpf/helpers: bpf_strnstr: Exact match length
Rtoax Aug 29, 2025
5e20e93
selftests/bpf: Add tests for bpf_strnstr
Rtoax Aug 29, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
10 changes: 9 additions & 1 deletion kernel/bpf/helpers.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -3672,10 +3672,18 @@ __bpf_kfunc int bpf_strnstr(const char *s1__ign, const char *s2__ign, size_t len

guard(pagefault)();
for (i = 0; i < XATTR_SIZE_MAX; i++) {
for (j = 0; i + j < len && j < XATTR_SIZE_MAX; j++) {
for (j = 0; i + j <= len && j < XATTR_SIZE_MAX; j++) {
__get_kernel_nofault(&c2, s2__ign + j, char, err_out);
if (c2 == '\0')
return i;
/**
* corner case i+j==len to ensure that we matched
* entire s2. for example, param len=3:
* s1: A B C D E F -> i==1
* s2: B C D -> j==2
*/
if (i + j == len)
break;
__get_kernel_nofault(&c1, s1__ign + j, char, err_out);
if (c1 == '\0')
return -ENOENT;
Expand Down
8 changes: 6 additions & 2 deletions tools/testing/selftests/bpf/progs/string_kfuncs_success.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -30,8 +30,12 @@ __test(2) int test_strcspn(void *ctx) { return bpf_strcspn(str, "lo"); }
__test(6) int test_strstr_found(void *ctx) { return bpf_strstr(str, "world"); }
__test(-ENOENT) int test_strstr_notfound(void *ctx) { return bpf_strstr(str, "hi"); }
__test(0) int test_strstr_empty(void *ctx) { return bpf_strstr(str, ""); }
__test(0) int test_strnstr_found(void *ctx) { return bpf_strnstr(str, "hello", 6); }
__test(-ENOENT) int test_strnstr_notfound(void *ctx) { return bpf_strnstr(str, "hi", 10); }
__test(0) int test_strnstr_found1(void *ctx) { return bpf_strnstr("", "", 0); }
__test(0) int test_strnstr_found2(void *ctx) { return bpf_strnstr(str, "hello", 5); }
__test(0) int test_strnstr_found3(void *ctx) { return bpf_strnstr(str, "hello", 6); }
__test(-ENOENT) int test_strnstr_notfound1(void *ctx) { return bpf_strnstr(str, "hi", 10); }
__test(-ENOENT) int test_strnstr_notfound2(void *ctx) { return bpf_strnstr(str, "hello", 4); }
__test(-ENOENT) int test_strnstr_notfound3(void *ctx) { return bpf_strnstr("", "a", 0); }
__test(0) int test_strnstr_empty(void *ctx) { return bpf_strnstr(str, "", 1); }

char _license[] SEC("license") = "GPL";
Loading