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arm64: uaccess: ensure extension of access_ok() addr

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commit a06040d7a791a9177581dcf7293941bd92400856 upstream.

Our access_ok() simply hands its arguments over to __range_ok(), which
implicitly assummes that the addr parameter is 64 bits wide. This isn't
necessarily true for compat code, which might pass down a 32-bit address
parameter.

In these cases, we don't have a guarantee that the address has been zero
extended to 64 bits, and the upper bits of the register may contain
unknown values, potentially resulting in a suprious failure.

Avoid this by explicitly casting the addr parameter to an unsigned long
(as is done on other architectures), ensuring that the parameter is
widened appropriately.

Fixes: 0aea86a217 ("arm64: User access library functions")
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Mark Rutland 2017-05-03 16:09:35 +01:00 • committed by Greg Kroah-Hartman
parent c23fee69f5
commit 06dd8281a7
1 changed files with 2 additions and 1 deletions
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3
arch/arm64/include/asm/uaccess.h
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@ -92,11 +92,12 @@ static inline void set_fs(mm_segment_t fs)
*/ */
#define __range_ok(addr, size) \ #define __range_ok(addr, size) \
({ \ ({ \
unsigned long __addr = (unsigned long __force)(addr); \
unsigned long flag, roksum; \ unsigned long flag, roksum; \
__chk_user_ptr(addr); \ __chk_user_ptr(addr); \
asm("adds %1, %1, %3; ccmp %1, %4, #2, cc; cset %0, ls" \ asm("adds %1, %1, %3; ccmp %1, %4, #2, cc; cset %0, ls" \
: "=&r" (flag), "=&r" (roksum) \ : "=&r" (flag), "=&r" (roksum) \
: "1" (addr), "Ir" (size), \ : "1" (__addr), "Ir" (size), \
"r" (current_thread_info()->addr_limit) \ "r" (current_thread_info()->addr_limit) \
: "cc"); \ : "cc"); \
flag; \ flag; \