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authorJames Hogan <james.hogan@imgtec.com>2017-03-31 11:23:18 +0100
committerJames Hogan <james.hogan@imgtec.com>2017-04-05 14:49:36 +0100
commit2257211942bbbf6c798ab70b487d7e62f7835a1a (patch)
treec07090df7fa8bc3d72473de87caede42cc1c7226 /arch/metag
parentef62a2d81f73d9cddef14bc3d9097a57010d551c (diff)
metag/usercopy: Fix alignment error checking
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 Cc: stable@vger.kernel.org
Diffstat (limited to 'arch/metag')
-rw-r--r--arch/metag/lib/usercopy.c10
1 files changed, 4 insertions, 6 deletions
diff --git a/arch/metag/lib/usercopy.c b/arch/metag/lib/usercopy.c
index b4eb1f17069f..a6ced9691ddb 100644
--- a/arch/metag/lib/usercopy.c
+++ b/arch/metag/lib/usercopy.c
@@ -717,6 +717,8 @@ unsigned long __copy_user_zeroing(void *pdst, const void __user *psrc,
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 *pdst, const void __user *psrc,
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 *pdst, const void __user *psrc,
}
}
- /* 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)) {