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authorChen, Kenneth W <kenneth.w.chen@intel.com>2005-09-06 16:05:23 -0700
committerTony Luck <tony.luck@intel.com>2005-09-07 08:53:16 -0700
commit295bd89279aad6959f0d363ee8e946d4766f9ad8 (patch)
treee0bcc6080adc665a818585fbb0280a50c82a18c4 /arch/ia64/lib/memcpy_mck.S
parent63028aa7f581d9d4e6889f9dc06ded2534250a76 (diff)
downloadlinux-2.6.38-lt-ux500-295bd89279aad6959f0d363ee8e946d4766f9ad8.tar.gz
[IA64] make exception handler in copy_user more robust
The exception handler in copy user always expects fault occurs only on user space address and the fall back recovery code is written with that very assumption in mind. Recent source code inspection revealed that while it worked splendid and to the expectation under normal circumstances, It broke down under unexpected condition where some address calculation might go outside the legal address range the original copy_user was called for. This patch is to make copy_user exception handler more robust and to prevent potential memory corruption. Signed-off-by: Ken Chen <kenneth.w.chen@intel.com> Signed-off-by: Tony Luck <tony.luck@intel.com>
Diffstat (limited to 'arch/ia64/lib/memcpy_mck.S')
-rw-r--r--arch/ia64/lib/memcpy_mck.S3
1 files changed, 3 insertions, 0 deletions
diff --git a/arch/ia64/lib/memcpy_mck.S b/arch/ia64/lib/memcpy_mck.S
index 6f308e62c13..46c9331e7ab 100644
--- a/arch/ia64/lib/memcpy_mck.S
+++ b/arch/ia64/lib/memcpy_mck.S
@@ -625,8 +625,11 @@ EK(.ex_handler, (p17) st8 [dst1]=r39,8); \
clrrrb
;;
alloc saved_pfs_stack=ar.pfs,3,3,3,0
+ cmp.lt p8,p0=A,r0
sub B = dst0, saved_in0 // how many byte copied so far
;;
+(p8) mov A = 0; // A shouldn't be negative, cap it
+ ;;
sub C = A, B
sub D = saved_in2, A
;;