This is a note to let you know that I've just added the patch titled
mm: fix vm_brk_flags() to not bail out while holding lock
to the 6.5-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
mm-fix-vm_brk_flags-to-not-bail-out-while-holding-lock.patch
and it can be found in the queue-6.5 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From e0f81ab1e4f42ffece6440dc78f583eb352b9a71 Mon Sep 17 00:00:00 2001
From: Sebastian Ott <sebott@xxxxxxxxxx>
Date: Fri, 29 Sep 2023 10:19:41 -0700
Subject: mm: fix vm_brk_flags() to not bail out while holding lock
From: Sebastian Ott <sebott@xxxxxxxxxx>
commit e0f81ab1e4f42ffece6440dc78f583eb352b9a71 upstream.
Calling vm_brk_flags() with flags set other than VM_EXEC will exit the
function without releasing the mmap_write_lock.
Just do the sanity check before the lock is acquired. This doesn't fix an
actual issue since no caller sets a flag other than VM_EXEC.
Link: https://lkml.kernel.org/r/20230929171937.work.697-kees@xxxxxxxxxx
Fixes: 2e7ce7d354f2 ("mm/mmap: change do_brk_flags() to expand existing VMA and add do_brk_munmap()")
Signed-off-by: Sebastian Ott <sebott@xxxxxxxxxx>
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
Reviewed-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
Cc: Yu Zhao <yuzhao@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
mm/mmap.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -3136,13 +3136,13 @@ int vm_brk_flags(unsigned long addr, uns
if (!len)
return 0;
- if (mmap_write_lock_killable(mm))
- return -EINTR;
-
/* Until we need other flags, refuse anything except VM_EXEC. */
if ((flags & (~VM_EXEC)) != 0)
return -EINVAL;
+ if (mmap_write_lock_killable(mm))
+ return -EINTR;
+
ret = check_brk_limits(addr, len);
if (ret)
goto limits_failed;
Patches currently in stable-queue which might be from sebott@xxxxxxxxxx are
queue-6.5/mm-fix-vm_brk_flags-to-not-bail-out-while-holding-lock.patch
