Skip to content

gh-134070: Prevent out-of-bounds read in mi_clz32 and mi_ctz32 #134149

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

Open
wants to merge 8 commits into
base: main
Choose a base branch
from
+30 −23
Open

gh-134070: Prevent out-of-bounds read in mi_clz32 and mi_ctz32 #134149

Changes from 1 commit
Commits
Show all changes
8 commits
Select commit Hold shift + click to select a range
e8466b0
Fix: Prevent out-of-bounds read in mi_clz32 and mi_ctz32 (#134070)
vedant713 May 17, 2025
3658bc3
Merge branch 'main' into fix-mimalloc-bug
vedant713 May 17, 2025
64e9718
gh-134070: Add news entry for mimalloc out-of-bounds fix
vedant713 May 17, 2025
c961fa0
gh-134070: Add news entry for mimalloc out-of-bounds fix
vedant713 May 17, 2025
911c128
gh-134070: Add news entry for mimalloc out-of-bounds fix
vedant713 May 17, 2025
bce07b2
gh-134070: Add news entry for mimalloc out-of-bounds fix
vedant713 May 17, 2025
bd186c9
Update internal.h
vedant713 Jul 13, 2025
796a176
Update internal.h
vedant713 Jul 13, 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
6 changes: 4 additions & 2 deletions Include/internal/mimalloc/mimalloc/internal.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -851,7 +851,8 @@ static inline size_t mi_ctz32(uint32_t x) {
31, 27, 13, 23, 21, 19, 16, 7, 26, 12, 18, 6, 11, 5, 10, 9
};
if (x==0) return 32;
return debruijn[((x & -(int32_t)x) * 0x077CB531UL) >> 27];
return debruijn[(uint32_t)(((x & -(int32_t)x) * 0x077CB531UL) >> 27) & 31];

}
static inline size_t mi_clz32(uint32_t x) {
// de Bruijn multiplication, see <http://supertech.csail.mit.edu/papers/debruijn.pdf>
Expand All @@ -865,7 +866,8 @@ static inline size_t mi_clz32(uint32_t x) {
x |= x >> 4;
x |= x >> 8;
x |= x >> 16;
return debruijn[(uint32_t)(x * 0x07C4ACDDUL) >> 27];
return debruijn[(uint32_t)(x * 0x07C4ACDDUL >> 27) & 31];

}

static inline size_t mi_clz(uintptr_t x) {
Expand Down
Loading