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| author |   Rich Felker <dalias@libc.org> | 2020-08-28 21:01:41 -0400 |
|---|---|---|
| committer | Rich Felker <dalias@libc.org> | 2020-09-13 21:22:55 -0400 |
| commit | b0cfc315ff38c423a5ce9ce159bd5baa4135e688 (patch) | |
| tree | d644d9e035223476718925fee68c57f1d13719a9 /arch/sh/kernel/entry-common.S | |
| parent | sh: remove spurious circular inclusion from asm/smp.h (diff) | |
| download | linux-dev-b0cfc315ff38c423a5ce9ce159bd5baa4135e688.tar.xz linux-dev-b0cfc315ff38c423a5ce9ce159bd5baa4135e688.zip | |
sh: fix syscall tracing
Addition of SECCOMP_FILTER exposed a longstanding bug in
do_syscall_trace_enter, whereby r0 (the 5th argument register) was
mistakenly used where r3 (syscall_nr) was intended. By overwriting r0
rather than r3 with -1 when attempting to block a syscall, the
existing code would instead have caused the syscall to execute with an
argument clobbered.
Commit 0bb605c2c7f2b4b3 then introduced skipping of the syscall when
do_syscall_trace_enter returns -1, so that the return value set by
seccomp filters would not be clobbered by -ENOSYS. This eliminated the
clobbering of the 5th argument register, but instead caused syscalls
made with a 5th argument of -1 to be misinterpreted as a request by
do_syscall_trace_enter to suppress the syscall.
Fixes: 0bb605c2c7f2b4b3 ("sh: Add SECCOMP_FILTER")
Fixes: ab99c733ae73cce3 ("sh: Make syscall tracer use tracehook notifiers, add TIF_NOTIFY_RESUME.")
Tested-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Signed-off-by: Rich Felker <dalias@libc.org>
Diffstat (limited to 'arch/sh/kernel/entry-common.S')
| -rw-r--r-- | arch/sh/kernel/entry-common.S | 1 |
1 files changed, 0 insertions, 1 deletions
diff --git a/arch/sh/kernel/entry-common.S b/arch/sh/kernel/entry-common.S index ad963104d22d..91ab2607a1ff 100644 --- a/arch/sh/kernel/entry-common.S +++ b/arch/sh/kernel/entry-common.S @@ -370,7 +370,6 @@ syscall_trace_entry: nop cmp/eq #-1, r0 bt syscall_exit - mov.l r0, @(OFF_R0,r15) ! Save return value ! Reload R0-R4 from kernel stack, where the ! parent may have modified them using ! ptrace(POKEUSR). (Note that R0-R2 are |