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Message-ID: <20240807173336.2523757-2-pedro.falcato@gmail.com>
Date: Wed, 7 Aug 2024 18:33:35 +0100
From: Pedro Falcato <pedro.falcato@...il.com>
To: Andrew Morton <akpm@...ux-foundation.org>,
Shuah Khan <shuah@...nel.org>,
"Liam R. Howlett" <Liam.Howlett@...cle.com>,
Jeff Xu <jeffxu@...omium.org>,
Kees Cook <kees@...nel.org>,
linux-mm@...ck.org
Cc: linux-kernel@...r.kernel.org,
linux-kselftest@...r.kernel.org,
Pedro Falcato <pedro.falcato@...il.com>,
stable@...r.kernel.org
Subject: [PATCH 1/2] mseal: Fix is_madv_discard()
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. This is obviously incorrect, so use
a switch statement instead.
Cc: stable@...r.kernel.org
Fixes: 8be7258aad44 ("mseal: add mseal syscall")
Signed-off-by: Pedro Falcato <pedro.falcato@...il.com>
---
mm/mseal.c | 14 +++++++++++---
1 file changed, 11 insertions(+), 3 deletions(-)
diff --git a/mm/mseal.c b/mm/mseal.c
index bf783bba8ed..15bba28acc0 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)
--
2.46.0
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