From: Roland McGrath Date: Wed, 5 Sep 2007 10:05:56 +0000 (-0700) Subject: Fix spurious syscall tracing after PTRACE_DETACH + PTRACE_ATTACH X-Git-Tag: v2.6.23-rc6~8 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=7d94143291e4e625e2bc3b1ebdc7143ee7a9a2f1;p=pandora-kernel.git Fix spurious syscall tracing after PTRACE_DETACH + PTRACE_ATTACH 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 Signed-off-by: Linus Torvalds --- Reading git-diff-tree failed