| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.10 035/110] metag/usercopy: Fix alignment error checking | Date | Mon, 10 Apr 2017 18:42:26 +0200 |
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4.10-stable review patch. If anyone has any objections, please let me know.
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From: James Hogan <james.hogan@imgtec.com>
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@imgtec.com> Cc: linux-metag@vger.kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- 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)) {
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