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author | Rich Felker <dalias@libc.org> | 2020-08-28 21:01:41 -0400 |
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committer | Rich Felker <dalias@libc.org> | 2020-09-13 21:22:55 -0400 |
commit | b0cfc315ff38c423a5ce9ce159bd5baa4135e688 (patch) | |
tree | d644d9e035223476718925fee68c57f1d13719a9 /arch/sh/kernel/smp.c | |
parent | ca6345de57a46ba1bd35bd15b0ceb42e05b3d71f (diff) |
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/smp.c')
0 files changed, 0 insertions, 0 deletions