arm64: armv8_deprecated: ensure extension of addr

commit 55de49f9aa17b0b2b144dd2af587177b9aadf429 upstream.

Our compat swp emulation holds the compat user address in an unsigned
int, which it passes to __user_swpX_asm(). When a 32-bit value is passed
in a register, the upper 32 bits of the register are unknown, and we
must extend the value to 64 bits before we can use it as a base address.

This patch casts the address to unsigned long to ensure it has been
suitably extended, avoiding the potential issue, and silencing a related
warning from clang.

Fixes: bd35a4adc413 ("arm64: Port SWP/SWPB emulation support from arm")
Cc: <stable@vger.kernel.org> # 3.19.x-
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>

diff --git a/arch/arm64/kernel/armv8_deprecated.c b/arch/arm64/kernel/armv8_deprecated.c
index 937f5e58a4d340a27234c76b5a84fedcf9aa6373..478a00b9732b4c26f6fe1d41d56442044bc9e1f6 100644 (file)
--- a/arch/arm64/kernel/armv8_deprecated.c
+++ b/arch/arm64/kernel/armv8_deprecated.c
@@ -305,7 +305,8 @@ static void register_insn_emulation_sysctl(struct ctl_table *table)
        ALTERNATIVE("nop", SET_PSTATE_PAN(1), ARM64_HAS_PAN,    \
                CONFIG_ARM64_PAN)                               \
        : "=&r" (res), "+r" (data), "=&r" (temp)                \
-       : "r" (addr), "i" (-EAGAIN), "i" (-EFAULT)              \
+       : "r" ((unsigned long)addr), "i" (-EAGAIN),             \
+         "i" (-EFAULT)                                         \
        : "memory")
 
 #define __user_swp_asm(data, addr, res, temp) \