This is a note to let you know that I've just added the patch titled

MIPS: Drop spurious __unused in struct compat_flock

to the 4.15-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: mips-drop-spurious-__unused-in-struct-compat_flock.patch and it can be found in the queue-4.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From 6ae1756faddefd7494353380ee546dd38c2f97eb Mon Sep 17 00:00:00 2001

From: James Hogan jhogan@kernel.org Date: Tue, 20 Feb 2018 15:44:37 +0000 Subject: MIPS: Drop spurious __unused in struct compat_flock

From: James Hogan jhogan@kernel.org

commit 6ae1756faddefd7494353380ee546dd38c2f97eb upstream.

MIPS' struct compat_flock doesn't match the 32-bit struct flock, as it has an extra short __unused before pad[4], which combined with alignment increases the size to 40 bytes compared with struct flock's 36 bytes.

Since commit 8c6657cb50cb ("Switch flock copyin/copyout primitives to copy_{from,to}_user()"), put_compat_flock() writes the full compat_flock struct to userland, which results in corruption of the userland word after the struct flock when running 32-bit userlands on 64-bit kernels.

This was observed to cause a bus error exception when starting Firefox on Debian 8 (Jessie).

Reported-by: Peter Mamonov pmamonov@gmail.com Signed-off-by: James Hogan jhogan@kernel.org Tested-by: Peter Mamonov pmamonov@gmail.com Cc: Ralf Baechle ralf@linux-mips.org Cc: Al Viro viro@zeniv.linux.org.uk Cc: linux-mips@linux-mips.org Cc: stable@vger.kernel.org # 4.13+ Patchwork: https://patchwork.linux-mips.org/patch/18646/ Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org

--- arch/mips/include/asm/compat.h | 1 - 1 file changed, 1 deletion(-)

--- a/arch/mips/include/asm/compat.h +++ b/arch/mips/include/asm/compat.h @@ -86,7 +86,6 @@ struct compat_flock { compat_off_t l_len; s32 l_sysid; compat_pid_t l_pid; - short __unused; s32 pad[4]; };

Patches currently in stable-queue which might be from jhogan@kernel.org are

queue-4.15/mips-drop-spurious-__unused-in-struct-compat_flock.patch