mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2025-01-09 14:43:16 +00:00
7d94143291
When PTRACE_SYSCALL was used and then PTRACE_DETACH is used, the TIF_SYSCALL_TRACE flag is left set on the formerly-traced task. This means that when a new tracer comes along and does PTRACE_ATTACH, it's possible he gets a syscall tracing stop even though he's never used PTRACE_SYSCALL. This happens if the task was in the middle of a system call when the second PTRACE_ATTACH was done. The symptom is an unexpected SIGTRAP when the tracer thinks that only SIGSTOP should have been provoked by his ptrace calls so far. A few machines already fixed this in ptrace_disable (i386, ia64, m68k). But all other machines do not, and still have this bug. On x86_64, this constitutes a regression in IA32 compatibility support. Since all machines now use TIF_SYSCALL_TRACE for this, I put the clearing of TIF_SYSCALL_TRACE in the generic ptrace_detach code rather than adding it to every other machine's ptrace_disable. Signed-off-by: Roland McGrath <roland@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>