[2/3] arm64: compat: Don't pull syscall number from regs in arm_compat_syscall

Message ID 1546539240-20647-3-git-send-email-will.deacon@arm.com
State Accepted
Commit 53290432145a8eb143fe29e06e9c1465d43dc723
Headers show
Series
  • [1/3] arm64: compat: Avoid sending SIGILL for unallocated syscall numbers
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Commit Message

Will Deacon Jan. 3, 2019, 6:13 p.m.
The syscall number may have been changed by a tracer, so we should pass
the actual number in from the caller instead of pulling it from the
saved r7 value directly.

Cc: <stable@vger.kernel.org>
Cc: Dave Martin <Dave.Martin@arm.com>
Cc: Pi-Hsun Shih <pihsun@chromium.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>

---
 arch/arm64/kernel/sys_compat.c | 9 ++++-----
 arch/arm64/kernel/syscall.c    | 9 ++++-----
 2 files changed, 8 insertions(+), 10 deletions(-)

-- 
2.1.4

Comments

Dave Martin Jan. 4, 2019, 12:37 p.m. | #1
On Thu, Jan 03, 2019 at 06:13:59PM +0000, Will Deacon wrote:
> The syscall number may have been changed by a tracer, so we should pass

> the actual number in from the caller instead of pulling it from the

> saved r7 value directly.


Reviewed-by: Dave Martin <Dave.Martin@arm.com>


I was confused by the history here: commit 4141c857fd09 ("arm64: convert
raw syscall invocation to C") breaks syscall changing via
discarding the return from syscall_trace_enter() (which would also break
this case for compat), but the subsequent patch that migrates the
syscall code to C appears to fix it again.

> 

> Cc: <stable@vger.kernel.org>

> Cc: Dave Martin <Dave.Martin@arm.com>

> Cc: Pi-Hsun Shih <pihsun@chromium.org>

> Signed-off-by: Will Deacon <will.deacon@arm.com>

> ---

>  arch/arm64/kernel/sys_compat.c | 9 ++++-----

>  arch/arm64/kernel/syscall.c    | 9 ++++-----

>  2 files changed, 8 insertions(+), 10 deletions(-)

> 

> diff --git a/arch/arm64/kernel/sys_compat.c b/arch/arm64/kernel/sys_compat.c

> index 5972b7533fa0..54c29cd38ff9 100644

> --- a/arch/arm64/kernel/sys_compat.c

> +++ b/arch/arm64/kernel/sys_compat.c

> @@ -66,12 +66,11 @@ do_compat_cache_op(unsigned long start, unsigned long end, int flags)

>  /*

>   * Handle all unrecognised system calls.

>   */

> -long compat_arm_syscall(struct pt_regs *regs)

> +long compat_arm_syscall(struct pt_regs *regs, int scno)

>  {

> -	unsigned int no = regs->regs[7];

>  	void __user *addr;

>  

> -	switch (no) {

> +	switch (scno) {

>  	/*

>  	 * Flush a region from virtual address 'r0' to virtual address 'r1'

>  	 * _exclusive_.  There is no alignment requirement on either address;

> @@ -107,7 +106,7 @@ long compat_arm_syscall(struct pt_regs *regs)

>  		 * way the calling program can gracefully determine whether

>  		 * a feature is supported.

>  		 */

> -		if (no < __ARM_NR_compat_syscall_end)

> +		if (scno < __ARM_NR_compat_syscall_end)

>  			return -ENOSYS;

>  		break;

>  	}

> @@ -116,6 +115,6 @@ long compat_arm_syscall(struct pt_regs *regs)

>  		(compat_thumb_mode(regs) ? 2 : 4);

>  

>  	arm64_notify_die("Oops - bad compat syscall(2)", regs,

> -			 SIGILL, ILL_ILLTRP, addr, no);

> +			 SIGILL, ILL_ILLTRP, addr, scno);

>  	return 0;

>  }

> diff --git a/arch/arm64/kernel/syscall.c b/arch/arm64/kernel/syscall.c

> index 032d22312881..5610ac01c1ec 100644

> --- a/arch/arm64/kernel/syscall.c

> +++ b/arch/arm64/kernel/syscall.c

> @@ -13,16 +13,15 @@

>  #include <asm/thread_info.h>

>  #include <asm/unistd.h>

>  

> -long compat_arm_syscall(struct pt_regs *regs);

> -

> +long compat_arm_syscall(struct pt_regs *regs, int scno);

>  long sys_ni_syscall(void);

>  

> -asmlinkage long do_ni_syscall(struct pt_regs *regs)

> +static long do_ni_syscall(struct pt_regs *regs, int scno)

>  {

>  #ifdef CONFIG_COMPAT

>  	long ret;

>  	if (is_compat_task()) {

> -		ret = compat_arm_syscall(regs);

> +		ret = compat_arm_syscall(regs, scno);

>  		if (ret != -ENOSYS)

>  			return ret;

>  	}

> @@ -47,7 +46,7 @@ static void invoke_syscall(struct pt_regs *regs, unsigned int scno,

>  		syscall_fn = syscall_table[array_index_nospec(scno, sc_nr)];

>  		ret = __invoke_syscall(regs, syscall_fn);

>  	} else {

> -		ret = do_ni_syscall(regs);

> +		ret = do_ni_syscall(regs, scno);

>  	}

>  

>  	regs->regs[0] = ret;

> -- 

> 2.1.4

> 

> 

> _______________________________________________

> linux-arm-kernel mailing list

> linux-arm-kernel@lists.infradead.org

> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

Patch

diff --git a/arch/arm64/kernel/sys_compat.c b/arch/arm64/kernel/sys_compat.c
index 5972b7533fa0..54c29cd38ff9 100644
--- a/arch/arm64/kernel/sys_compat.c
+++ b/arch/arm64/kernel/sys_compat.c
@@ -66,12 +66,11 @@  do_compat_cache_op(unsigned long start, unsigned long end, int flags)
 /*
  * Handle all unrecognised system calls.
  */
-long compat_arm_syscall(struct pt_regs *regs)
+long compat_arm_syscall(struct pt_regs *regs, int scno)
 {
-	unsigned int no = regs->regs[7];
 	void __user *addr;
 
-	switch (no) {
+	switch (scno) {
 	/*
 	 * Flush a region from virtual address 'r0' to virtual address 'r1'
 	 * _exclusive_.  There is no alignment requirement on either address;
@@ -107,7 +106,7 @@  long compat_arm_syscall(struct pt_regs *regs)
 		 * way the calling program can gracefully determine whether
 		 * a feature is supported.
 		 */
-		if (no < __ARM_NR_compat_syscall_end)
+		if (scno < __ARM_NR_compat_syscall_end)
 			return -ENOSYS;
 		break;
 	}
@@ -116,6 +115,6 @@  long compat_arm_syscall(struct pt_regs *regs)
 		(compat_thumb_mode(regs) ? 2 : 4);
 
 	arm64_notify_die("Oops - bad compat syscall(2)", regs,
-			 SIGILL, ILL_ILLTRP, addr, no);
+			 SIGILL, ILL_ILLTRP, addr, scno);
 	return 0;
 }
diff --git a/arch/arm64/kernel/syscall.c b/arch/arm64/kernel/syscall.c
index 032d22312881..5610ac01c1ec 100644
--- a/arch/arm64/kernel/syscall.c
+++ b/arch/arm64/kernel/syscall.c
@@ -13,16 +13,15 @@ 
 #include <asm/thread_info.h>
 #include <asm/unistd.h>
 
-long compat_arm_syscall(struct pt_regs *regs);
-
+long compat_arm_syscall(struct pt_regs *regs, int scno);
 long sys_ni_syscall(void);
 
-asmlinkage long do_ni_syscall(struct pt_regs *regs)
+static long do_ni_syscall(struct pt_regs *regs, int scno)
 {
 #ifdef CONFIG_COMPAT
 	long ret;
 	if (is_compat_task()) {
-		ret = compat_arm_syscall(regs);
+		ret = compat_arm_syscall(regs, scno);
 		if (ret != -ENOSYS)
 			return ret;
 	}
@@ -47,7 +46,7 @@  static void invoke_syscall(struct pt_regs *regs, unsigned int scno,
 		syscall_fn = syscall_table[array_index_nospec(scno, sc_nr)];
 		ret = __invoke_syscall(regs, syscall_fn);
 	} else {
-		ret = do_ni_syscall(regs);
+		ret = do_ni_syscall(regs, scno);
 	}
 
 	regs->regs[0] = ret;