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ARM: 8802/1: Call syscall_trace_exit even when system call skipped

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On at least x86 and ARM64, and as documented in the ptrace man page
a skipped system call will still cause a syscall exit ptrace stop.

Previous to this commit 32-bit ARM did not, resulting in strace
being confused when seccomp skips system calls.

This change also impacts programs that use ptrace to skip system calls.

Fixes: ad75b51459 ("ARM: 7579/1: arch/allow a scno of -1 to not cause a SIGILL")
Signed-off-by: Timothy E Baldwin <T.E.Baldwin99@members.leeds.ac.uk>
Signed-off-by: Eugene Syromyatnikov <evgsyr@gmail.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Tested-by: Kees Cook <keescook@chromium.org>
Tested-by: Eugene Syromyatnikov <evgsyr@gmail.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
This commit is contained in:
Timothy E Baldwin 2018-10-08 19:26:48 +01:00 committed by Russell King
parent 8403bcb779
commit f18aef742c
1 changed files with 4 additions and 5 deletions
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9
arch/arm/kernel/entry-common.S
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@ -296,16 +296,15 @@ __sys_trace:
cmp scno, #-1 @ skip the syscall?
bne 2b
add sp, sp, #S_OFF @ restore stack
b ret_slow_syscall
__sys_trace_return:
str r0, [sp, #S_R0 + S_OFF]! @ save returned r0
__sys_trace_return_nosave:
enable_irq_notrace
mov r0, sp
bl syscall_trace_exit
b ret_slow_syscall
__sys_trace_return_nosave:
enable_irq_notrace
__sys_trace_return:
str r0, [sp, #S_R0 + S_OFF]! @ save returned r0
mov r0, sp
bl syscall_trace_exit
b ret_slow_syscall