This is a note to let you know that I've just added the patch titled
uprobes: Fix mmap_region()'s mm->mm_rb corruption if uprobe_mmap() fails
to the 3.5-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:
uprobes-fix-mmap_region-s-mm-mm_rb-corruption-if-uprobe_mmap-fails.patch
and it can be found in the queue-3.5 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From c7a3a88c938fbe3d70c2278e082b80eb830d1c58 Mon Sep 17 00:00:00 2001
From: Oleg Nesterov <[email protected]>
Date: Sun, 19 Aug 2012 19:10:42 +0200
Subject: uprobes: Fix mmap_region()'s mm->mm_rb corruption if uprobe_mmap()
fails
From: Oleg Nesterov <[email protected]>
commit c7a3a88c938fbe3d70c2278e082b80eb830d1c58 upstream.
This patch fixes:
https://bugzilla.redhat.com/show_bug.cgi?id=843640
If mmap_region()->uprobe_mmap() fails, unmap_and_free_vma path
does unmap_region() but does not remove the soon-to-be-freed vma
from rb tree. Actually there are more problems but this is how
William noticed this bug.
Perhaps we could do do_munmap() + return in this case, but in
fact it is simply wrong to abort if uprobe_mmap() fails. Until
at least we move the !UPROBE_COPY_INSN code from
install_breakpoint() to uprobe_register().
For example, uprobe_mmap()->install_breakpoint() can fail if the
probed insn is not supported (remember, uprobe_register()
succeeds if nobody mmaps inode/offset), mmap() should not fail
in this case.
dup_mmap()->uprobe_mmap() is wrong too by the same reason,
fork() can race with uprobe_register() and fail for no reason if
it wins the race and does install_breakpoint() first.
And, if nothing else, both mmap_region() and dup_mmap() return
success if uprobe_mmap() fails. Change them to ignore the error
code from uprobe_mmap().
Reported-and-tested-by: William Cohen <[email protected]>
Signed-off-by: Oleg Nesterov <[email protected]>
Acked-by: Srikar Dronamraju <[email protected]>
Cc: Anton Arapov <[email protected]>
Cc: William Cohen <[email protected]>
Cc: Linus Torvalds <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
kernel/fork.c | 4 ++--
mm/mmap.c | 5 ++---
2 files changed, 4 insertions(+), 5 deletions(-)
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -459,8 +459,8 @@ static int dup_mmap(struct mm_struct *mm
if (retval)
goto out;
- if (file && uprobe_mmap(tmp))
- goto out;
+ if (file)
+ uprobe_mmap(tmp);
}
/* a new mm has just been created */
arch_dup_mmap(oldmm, mm);
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1355,9 +1355,8 @@ out:
} else if ((flags & MAP_POPULATE) && !(flags & MAP_NONBLOCK))
make_pages_present(addr, addr + len);
- if (file && uprobe_mmap(vma))
- /* matching probes but cannot insert */
- goto unmap_and_free_vma;
+ if (file)
+ uprobe_mmap(vma);
return addr;
Patches currently in stable-queue which might be from [email protected] are
queue-3.5/uprobes-fix-mmap_region-s-mm-mm_rb-corruption-if-uprobe_mmap-fails.patch
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