| From | Luis Henriques <> | Subject | [PATCH 081/150] x86-64: Fix the failure case in copy_user_handle_tail() | Date | Tue, 26 Mar 2013 15:19:40 +0000 |
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3.5.7.9 -stable review patch. If anyone has any objections, please let me know.
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From: CQ Tang <cq.tang@intel.com>
commit 66db3feb486c01349f767b98ebb10b0c3d2d021b upstream.
The increment of "to" in copy_user_handle_tail() will have incremented before a failure has been noted. This causes us to skip a byte in the failure case.
Only do the increment when assured there is no failure.
Signed-off-by: CQ Tang <cq.tang@intel.com> Link: http://lkml.kernel.org/r/20130318150221.8439.993.stgit@phlsvslse11.ph.intel.com Signed-off-by: Mike Marciniszyn <mike.marciniszyn@intel.com> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> Signed-off-by: Luis Henriques <luis.henriques@canonical.com> --- arch/x86/lib/usercopy_64.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/x86/lib/usercopy_64.c b/arch/x86/lib/usercopy_64.c index e5b130b..cc9de31 100644 --- a/arch/x86/lib/usercopy_64.c +++ b/arch/x86/lib/usercopy_64.c @@ -72,10 +72,10 @@ copy_user_handle_tail(char *to, char *from, unsigned len, unsigned zerorest) char c; unsigned zero_len; - for (; len; --len) { + for (; len; --len, to++) { if (__get_user_nocheck(c, from++, sizeof(char))) break; - if (__put_user_nocheck(c, to++, sizeof(char))) + if (__put_user_nocheck(c, to, sizeof(char))) break; } -- 1.8.1.2
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