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| author | Gerald Schaefer <gerald.schaefer@de.ibm.com> | 2010-05-12 09:32:12 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2010-05-26 14:29:16 -0700 |
| commit | fa157eec79e78a875790df6faf53b3501c33a462 (patch) | |
| tree | 47723c9751ca71677228c183db3c829f85b39e32 | |
| parent | ee7a0b92fcc8d1ab43cff3dd75baeb2f646a93ff (diff) | |
| download | lwn-fa157eec79e78a875790df6faf53b3501c33a462.tar.gz lwn-fa157eec79e78a875790df6faf53b3501c33a462.zip | |
ptrace: fix return value of do_syscall_trace_enter()
commit 545c174d1f093a462b4bb9131b23d5ea72a600e1 upstream.
strace may change the system call number, so regs->gprs[2] must not
be read before tracehook_report_syscall_entry(). This fixes a bug
where "strace -f" will hang after a vfork().
Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
| -rw-r--r-- | arch/s390/kernel/ptrace.c | 5 |
1 files changed, 2 insertions, 3 deletions
diff --git a/arch/s390/kernel/ptrace.c b/arch/s390/kernel/ptrace.c index 653c6a178740..08f883842e21 100644 --- a/arch/s390/kernel/ptrace.c +++ b/arch/s390/kernel/ptrace.c @@ -632,7 +632,7 @@ long compat_arch_ptrace(struct task_struct *child, compat_long_t request, asmlinkage long do_syscall_trace_enter(struct pt_regs *regs) { - long ret; + long ret = 0; /* Do the secure computing check first. */ secure_computing(regs->gprs[2]); @@ -641,7 +641,6 @@ asmlinkage long do_syscall_trace_enter(struct pt_regs *regs) * The sysc_tracesys code in entry.S stored the system * call number to gprs[2]. */ - ret = regs->gprs[2]; if (test_thread_flag(TIF_SYSCALL_TRACE) && (tracehook_report_syscall_entry(regs) || regs->gprs[2] >= NR_syscalls)) { @@ -663,7 +662,7 @@ asmlinkage long do_syscall_trace_enter(struct pt_regs *regs) regs->gprs[2], regs->orig_gpr2, regs->gprs[3], regs->gprs[4], regs->gprs[5]); - return ret; + return ret ?: regs->gprs[2]; } asmlinkage void do_syscall_trace_exit(struct pt_regs *regs) |