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s390/ptrace: return -ENOSYS when invalid syscall is supplied

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commit cd29fa798001075a554b978df3a64e6656c25794 upstream.

The current code returns the syscall number which an invalid
syscall number is supplied and tracing is enabled. This makes
the strace testsuite fail.

Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Link: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1895132
[krzysztof: adjusted the backport around missing ifdef CONFIG_SECCOMP,
 add Link and Fixes; apparently this should go with the referenced commit]
Fixes: 00332c16b160 ("s390/ptrace: pass invalid syscall numbers to tracing")
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Sven Schnelle 2020-03-06 13:18:31 +01:00 committed by Greg Kroah-Hartman
parent a7eb81c1d1
commit 835c8d688e
1 changed files with 12 additions and 5 deletions
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17
arch/s390/kernel/ptrace.c
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@ -867,6 +867,7 @@ long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
asmlinkage long do_syscall_trace_enter(struct pt_regs *regs)
{
unsigned long mask = -1UL;
long ret = -1;
/*
* The sysc_tracesys code in entry.S stored the system
@ -878,27 +879,33 @@ asmlinkage long do_syscall_trace_enter(struct pt_regs *regs)
* Tracing decided this syscall should not happen. Skip
* the system call and the system call restart handling.
*/
clear_pt_regs_flag(regs, PIF_SYSCALL);
return -1;
goto skip;
}
/* Do the secure computing check after ptrace. */
if (secure_computing(NULL)) {
/* seccomp failures shouldn't expose any additional code. */
return -1;
goto skip;
}
if (unlikely(test_thread_flag(TIF_SYSCALL_TRACEPOINT)))
trace_sys_enter(regs, regs->gprs[2]);
trace_sys_enter(regs, regs->int_code & 0xffff);
if (is_compat_task())
mask = 0xffffffff;
audit_syscall_entry(regs->gprs[2], regs->orig_gpr2 & mask,
audit_syscall_entry(regs->int_code & 0xffff, regs->orig_gpr2 & mask,
regs->gprs[3] &mask, regs->gprs[4] &mask,
regs->gprs[5] &mask);
if ((signed long)regs->gprs[2] >= NR_syscalls) {
regs->gprs[2] = -ENOSYS;
ret = -ENOSYS;
}
return regs->gprs[2];
skip:
clear_pt_regs_flag(regs, PIF_SYSCALL);
return ret;
}
asmlinkage void do_syscall_trace_exit(struct pt_regs *regs)