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authorPeter Zijlstra <peterz@infradead.org>2019-08-29 11:24:45 +0300
committerPeter Zijlstra <peterz@infradead.org>2019-09-02 15:22:38 +0300
commit9b8bd476e78e89c9ea26c3b435ad0201c3d7dbf5 (patch)
treeb9a0554a17fe68adb8624c7845fdb1d8e0d7d324 /arch
parent29d9a0b50736768f042752070e5cdf4e4d4c00df (diff)
downloadlinux-9b8bd476e78e89c9ea26c3b435ad0201c3d7dbf5.tar.xz
x86/uaccess: Don't leak the AC flags into __get_user() argument evaluation
Identical to __put_user(); the __get_user() argument evalution will too leak UBSAN crud into the __uaccess_begin() / __uaccess_end() region. While uncommon this was observed to happen for: drivers/xen/gntdev.c: if (__get_user(old_status, batch->status[i])) where UBSAN added array bound checking. This complements commit: 6ae865615fc4 ("x86/uaccess: Dont leak the AC flag into __put_user() argument evaluation") Tested-by Sedat Dilek <sedat.dilek@gmail.com> Reported-by: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Cc: broonie@kernel.org Cc: sfr@canb.auug.org.au Cc: akpm@linux-foundation.org Cc: Randy Dunlap <rdunlap@infradead.org> Cc: mhocko@suse.cz Cc: Josh Poimboeuf <jpoimboe@redhat.com> Link: https://lkml.kernel.org/r/20190829082445.GM2369@hirez.programming.kicks-ass.net
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/include/asm/uaccess.h4
1 files changed, 3 insertions, 1 deletions
diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h
index 9c4435307ff8..35c225ede0e4 100644
--- a/arch/x86/include/asm/uaccess.h
+++ b/arch/x86/include/asm/uaccess.h
@@ -444,8 +444,10 @@ __pu_label: \
({ \
int __gu_err; \
__inttype(*(ptr)) __gu_val; \
+ __typeof__(ptr) __gu_ptr = (ptr); \
+ __typeof__(size) __gu_size = (size); \
__uaccess_begin_nospec(); \
- __get_user_size(__gu_val, (ptr), (size), __gu_err, -EFAULT); \
+ __get_user_size(__gu_val, __gu_ptr, __gu_size, __gu_err, -EFAULT); \
__uaccess_end(); \
(x) = (__force __typeof__(*(ptr)))__gu_val; \
__builtin_expect(__gu_err, 0); \