This is a note to let you know that I've just added the patch titled
staging: android: ashmem: Fix mmap size validation
to the 4.18-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:
staging-android-ashmem-fix-mmap-size-validation.patch
and it can be found in the queue-4.18 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Sat Sep 29 04:24:28 PDT 2018
From: Alistair Strachan <astrachan@xxxxxxxxxx>
Date: Tue, 19 Jun 2018 17:57:35 -0700
Subject: staging: android: ashmem: Fix mmap size validation
From: Alistair Strachan <astrachan@xxxxxxxxxx>
[ Upstream commit 8632c614565d0c5fdde527889601c018e97b6384 ]
The ashmem driver did not check that the size/offset of the vma passed
to its .mmap() function was not larger than the ashmem object being
mapped. This could cause mmap() to succeed, even though accessing parts
of the mapping would later fail with a segmentation fault.
Ensure an error is returned by the ashmem_mmap() function if the vma
size is larger than the ashmem object size. This enables safer handling
of the problem in userspace.
Cc: Todd Kjos <tkjos@xxxxxxxxxxx>
Cc: devel@xxxxxxxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Cc: kernel-team@xxxxxxxxxxx
Cc: Joel Fernandes <joel@xxxxxxxxxxxxxxxxx>
Signed-off-by: Alistair Strachan <astrachan@xxxxxxxxxx>
Acked-by: Joel Fernandes (Google) <joel@xxxxxxxxxxxxxxxxx>
Reviewed-by: Martijn Coenen <maco@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/staging/android/ashmem.c | 6 ++++++
1 file changed, 6 insertions(+)
--- a/drivers/staging/android/ashmem.c
+++ b/drivers/staging/android/ashmem.c
@@ -366,6 +366,12 @@ static int ashmem_mmap(struct file *file
goto out;
}
+ /* requested mapping size larger than object size */
+ if (vma->vm_end - vma->vm_start > PAGE_ALIGN(asma->size)) {
+ ret = -EINVAL;
+ goto out;
+ }
+
/* requested protection bits must match our allowed protection mask */
if (unlikely((vma->vm_flags & ~calc_vm_prot_bits(asma->prot_mask, 0)) &
calc_vm_prot_bits(PROT_MASK, 0))) {
Patches currently in stable-queue which might be from astrachan@xxxxxxxxxx are
queue-4.18/staging-android-ashmem-fix-mmap-size-validation.patch
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