This is a note to let you know that I've just added the patch titled metag/usercopy: Fix alignment error checking to the 4.4-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: metag-usercopy-fix-alignment-error-checking.patch and it can be found in the queue-4.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 2257211942bbbf6c798ab70b487d7e62f7835a1a Mon Sep 17 00:00:00 2001 From: James Hogan <james.hogan@xxxxxxxxxx> Date: Fri, 31 Mar 2017 11:23:18 +0100 Subject: metag/usercopy: Fix alignment error checking From: James Hogan <james.hogan@xxxxxxxxxx> commit 2257211942bbbf6c798ab70b487d7e62f7835a1a upstream. Fix the error checking of the alignment adjustment code in raw_copy_from_user(), which mistakenly considers it safe to skip the error check when aligning the source buffer on a 2 or 4 byte boundary. If the destination buffer was unaligned it may have started to copy using byte or word accesses, which could well be at the start of a new (valid) source page. This would result in it appearing to have copied 1 or 2 bytes at the end of the first (invalid) page rather than none at all. Fixes: 373cd784d0fc ("metag: Memory handling") Signed-off-by: James Hogan <james.hogan@xxxxxxxxxx> Cc: linux-metag@xxxxxxxxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- arch/metag/lib/usercopy.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-) --- a/arch/metag/lib/usercopy.c +++ b/arch/metag/lib/usercopy.c @@ -717,6 +717,8 @@ unsigned long __copy_user_zeroing(void * if ((unsigned long) src & 1) { __asm_copy_from_user_1(dst, src, retn); n--; + if (retn) + goto copy_exception_bytes; } if ((unsigned long) dst & 1) { /* Worst case - byte copy */ @@ -730,6 +732,8 @@ unsigned long __copy_user_zeroing(void * if (((unsigned long) src & 2) && n >= 2) { __asm_copy_from_user_2(dst, src, retn); n -= 2; + if (retn) + goto copy_exception_bytes; } if ((unsigned long) dst & 2) { /* Second worst case - word copy */ @@ -741,12 +745,6 @@ unsigned long __copy_user_zeroing(void * } } - /* We only need one check after the unalignment-adjustments, - because if both adjustments were done, either both or - neither reference had an exception. */ - if (retn != 0) - goto copy_exception_bytes; - #ifdef USE_RAPF /* 64 bit copy loop */ if (!(((unsigned long) src | (unsigned long) dst) & 7)) { Patches currently in stable-queue which might be from james.hogan@xxxxxxxxxx are queue-4.4/mips-end-spinlocks-with-.insn.patch queue-4.4/metag-usercopy-add-missing-fixups.patch queue-4.4/metag-usercopy-add-early-abort-to-copy_to_user.patch queue-4.4/mips-ralink-fix-typos-in-rt3883-pinctrl.patch queue-4.4/metag-usercopy-set-flags-before-addz.patch queue-4.4/metag-usercopy-fix-src-fixup-in-from-user-rapf-loops.patch queue-4.4/metag-usercopy-drop-unused-macros.patch queue-4.4/mips-lantiq-fix-missing-xbar-kernel-panic.patch queue-4.4/metag-usercopy-zero-rest-of-buffer-from-copy_from_user.patch queue-4.4/metag-usercopy-fix-alignment-error-checking.patch queue-4.4/mips-force-o32-fp64-support-on-32bit-mips64r6-kernels.patch