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| author | Pedro Falcato <pedro.falcato@gmail.com> | 2024-08-07 18:33:35 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2024-08-29 17:35:39 +0200 |
| commit | 5fc922bef4efba7708635149cc9f8b2d864f9abe (patch) | |
| tree | 864e48bceb64c6cf0cd143e83c11f8baca80fb9a /mm | |
| parent | 6b980b0ab5c82fd255a0d56522f813d490e0767c (diff) | |
| download | linux-5fc922bef4efba7708635149cc9f8b2d864f9abe.tar.gz linux-5fc922bef4efba7708635149cc9f8b2d864f9abe.tar.bz2 linux-5fc922bef4efba7708635149cc9f8b2d864f9abe.zip | |
mseal: fix is_madv_discard()
commit e46bc2e7eb90a370bc27fa2fd98cb8251e7da1ec upstream.
is_madv_discard did its check wrong. MADV_ flags are not bitwise,
they're normal sequential numbers. So, for instance:
behavior & (/* ... */ | MADV_REMOVE)
tagged both MADV_REMOVE and MADV_RANDOM (bit 0 set) as discard
operations.
As a result the kernel could erroneously block certain madvises (e.g
MADV_RANDOM or MADV_HUGEPAGE) on sealed VMAs due to them sharing bits
with blocked MADV operations (e.g REMOVE or WIPEONFORK).
This is obviously incorrect, so use a switch statement instead.
Link: https://lkml.kernel.org/r/20240807173336.2523757-1-pedro.falcato@gmail.com
Link: https://lkml.kernel.org/r/20240807173336.2523757-2-pedro.falcato@gmail.com
Fixes: 8be7258aad44 ("mseal: add mseal syscall")
Signed-off-by: Pedro Falcato <pedro.falcato@gmail.com>
Tested-by: Jeff Xu <jeffxu@chromium.org>
Reviewed-by: Jeff Xu <jeffxu@chromium.org>
Cc: Kees Cook <kees@kernel.org>
Cc: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/mseal.c | 14 |
1 files changed, 11 insertions, 3 deletions
diff --git a/mm/mseal.c b/mm/mseal.c index bf783bba8ed0..15bba28acc00 100644 --- a/mm/mseal.c +++ b/mm/mseal.c @@ -40,9 +40,17 @@ static bool can_modify_vma(struct vm_area_struct *vma) static bool is_madv_discard(int behavior) { - return behavior & - (MADV_FREE | MADV_DONTNEED | MADV_DONTNEED_LOCKED | - MADV_REMOVE | MADV_DONTFORK | MADV_WIPEONFORK); + switch (behavior) { + case MADV_FREE: + case MADV_DONTNEED: + case MADV_DONTNEED_LOCKED: + case MADV_REMOVE: + case MADV_DONTFORK: + case MADV_WIPEONFORK: + return true; + } + + return false; } static bool is_ro_anon(struct vm_area_struct *vma) |