diff options
| author | James Hogan | 2017-06-29 10:12:36 +0100 |
|---|---|---|
| committer | Ralf Baechle | 2017-07-11 14:13:06 +0200 |
| commit | 828db212bf4b63c68c51f6519435c48e8d79bd00 (patch) | |
| tree | a617cc1577b8824d7c7b9ffd06be40b1f0f6b517 /arch/mips | |
| parent | becddba9f80f26a2b9ebe9bad2806304ed5e00e1 (diff) | |
MIPS: Traced negative syscalls should return -ENOSYS
If a negative system call number is used when system call tracing is
enabled, syscall_trace_enter() will return that negative system call
number without having written the return value and error flag into the
pt_regs.
The caller then treats it as a cancelled system call and assumes that
the return value and error flag are already written, leaving the
negative system call number in the return register ($v0), and the 4th
system call argument in the error register ($a3).
Add a special case to detect this at the end of syscall_trace_enter(),
to set the return value to error -ENOSYS when this happens.
Fixes: d218af78492a ("MIPS: scall: Always run the seccomp syscall filters")
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/16653/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Diffstat (limited to 'arch/mips')
| -rw-r--r-- | arch/mips/kernel/ptrace.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/arch/mips/kernel/ptrace.c b/arch/mips/kernel/ptrace.c index 8e2ea86dc23e..6dd13641a418 100644 --- a/arch/mips/kernel/ptrace.c +++ b/arch/mips/kernel/ptrace.c @@ -894,6 +894,13 @@ asmlinkage long syscall_trace_enter(struct pt_regs *regs, long syscall) audit_syscall_entry(syscall, regs->regs[4], regs->regs[5], regs->regs[6], regs->regs[7]); + + /* + * Negative syscall numbers are mistaken for rejected syscalls, but + * won't have had the return value set appropriately, so we do so now. + */ + if (syscall < 0) + syscall_set_return_value(current, regs, -ENOSYS, 0); return syscall; } |