The quilt patch titled
Subject: mseal: fix is_madv_discard()
has been removed from the -mm tree. Its filename was
mseal-fix-is_madv_discard.patch
This patch was dropped because it was merged into the mm-hotfixes-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
------------------------------------------------------
From: Pedro Falcato <pedro.falcato@xxxxxxxxx>
Subject: mseal: fix is_madv_discard()
Date: Wed, 7 Aug 2024 18:33:35 +0100
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@xxxxxxxxx
Link: https://lkml.kernel.org/r/20240807173336.2523757-2-pedro.falcato@xxxxxxxxx
Fixes: 8be7258aad44 ("mseal: add mseal syscall")
Signed-off-by: Pedro Falcato <pedro.falcato@xxxxxxxxx>
Tested-by: Jeff Xu <jeffxu@xxxxxxxxxxxx>
Reviewed-by: Jeff Xu <jeffxu@xxxxxxxxxxxx>
Cc: Kees Cook <kees@xxxxxxxxxx>
Cc: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
Cc: Shuah Khan <shuah@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/mseal.c | 14 +++++++++++---
1 file changed, 11 insertions(+), 3 deletions(-)
--- a/mm/mseal.c~mseal-fix-is_madv_discard
+++ a/mm/mseal.c
@@ -40,9 +40,17 @@ static bool can_modify_vma(struct vm_are
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)
_
Patches currently in -mm which might be from pedro.falcato@xxxxxxxxx are
selftests-mm-add-mseal-test-for-no-discard-madvise.patch
selftests-mm-add-mseal-test-for-no-discard-madvise-fix.patch
