From 5ec3444c8346c922316f4effafa8afc17defda0e Mon Sep 17 00:00:00 2001 From: Niklas Cassel Date: Mon, 9 Apr 2018 23:40:15 +0200 Subject: [PATCH] firmware: qcom: scm: Fix crash in qcom_scm_call_atomic1() qcom_scm_call_atomic1() can crash with a NULL pointer dereference at qcom_scm_call_atomic1+0x30/0x48. disassembly of qcom_scm_call_atomic1(): ... <0xc08d73b0 <+12>: ldr r3, [r12] ... (no instruction explicitly modifies r12) 0xc08d73cc <+40>: smc 0 ... (no instruction explicitly modifies r12) 0xc08d73d4 <+48>: ldr r3, [r12] <- crashing instruction ... Since the first ldr is successful, and since r12 isn't explicitly modified by any instruction between the first and the second ldr, it must have been modified by the smc call, which is ok, since r12 is caller save according to the AAPCS. Add r12 to the clobber list so that the compiler knows that the callee potentially overwrites the value in r12. Clobber descriptions may not in any way overlap with an input or output operand. Signed-off-by: Niklas Cassel Reviewed-by: Bjorn Andersson Reviewed-by: Stephen Boyd Signed-off-by: Andy Gross --- drivers/firmware/qcom_scm-32.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/drivers/firmware/qcom_scm-32.c b/drivers/firmware/qcom_scm-32.c index dfbd894..4e24e59 100644 --- a/drivers/firmware/qcom_scm-32.c +++ b/drivers/firmware/qcom_scm-32.c @@ -147,7 +147,7 @@ static u32 smc(u32 cmd_addr) "smc #0 @ switch to secure world\n" : "=r" (r0) : "r" (r0), "r" (r1), "r" (r2) - : "r3"); + : "r3", "r12"); } while (r0 == QCOM_SCM_INTERRUPTED); return r0; @@ -263,7 +263,7 @@ static s32 qcom_scm_call_atomic1(u32 svc, u32 cmd, u32 arg1) "smc #0 @ switch to secure world\n" : "=r" (r0) : "r" (r0), "r" (r1), "r" (r2) - : "r3"); + : "r3", "r12"); return r0; } @@ -298,7 +298,7 @@ static s32 qcom_scm_call_atomic2(u32 svc, u32 cmd, u32 arg1, u32 arg2) "smc #0 @ switch to secure world\n" : "=r" (r0) : "r" (r0), "r" (r1), "r" (r2), "r" (r3) - ); + : "r12"); return r0; } @@ -328,7 +328,7 @@ u32 qcom_scm_get_version(void) "smc #0 @ switch to secure world\n" : "=r" (r0), "=r" (r1) : "r" (r0), "r" (r1) - : "r2", "r3"); + : "r2", "r3", "r12"); } while (r0 == QCOM_SCM_INTERRUPTED); version = r1; -- 2.7.4