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authorOleg Nesterov <oleg@redhat.com>2013-07-09 01:01:05 +0200
committerLinus Torvalds <torvalds@linux-foundation.org>2013-07-09 19:33:26 +0200
commitfab840fc2d542fabcab903db8e03589a6702ba5f (patch)
tree26bd3ecf468ca83fa77e4b02d8c28371a995405d /kernel
parentptrace/x86: cleanup ptrace_set_debugreg() (diff)
downloadlinux-fab840fc2d542fabcab903db8e03589a6702ba5f.tar.xz
linux-fab840fc2d542fabcab903db8e03589a6702ba5f.zip
ptrace: PTRACE_DETACH should do flush_ptrace_hw_breakpoint(child)
Change ptrace_detach() to call flush_ptrace_hw_breakpoint(child). This frees the slots for non-ptrace PERF_TYPE_BREAKPOINT users, and this ensures that the tracee won't be killed by SIGTRAP triggered by the active breakpoints. Test-case: unsigned long encode_dr7(int drnum, int enable, unsigned int type, unsigned int len) { unsigned long dr7; dr7 = ((len | type) & 0xf) << (DR_CONTROL_SHIFT + drnum * DR_CONTROL_SIZE); if (enable) dr7 |= (DR_GLOBAL_ENABLE << (drnum * DR_ENABLE_SIZE)); return dr7; } int write_dr(int pid, int dr, unsigned long val) { return ptrace(PTRACE_POKEUSER, pid, offsetof (struct user, u_debugreg[dr]), val); } void func(void) { } int main(void) { int pid, stat; unsigned long dr7; pid = fork(); if (!pid) { assert(ptrace(PTRACE_TRACEME, 0,0,0) == 0); kill(getpid(), SIGHUP); func(); return 0x13; } assert(pid == waitpid(-1, &stat, 0)); assert(WSTOPSIG(stat) == SIGHUP); assert(write_dr(pid, 0, (long)func) == 0); dr7 = encode_dr7(0, 1, DR_RW_EXECUTE, DR_LEN_1); assert(write_dr(pid, 7, dr7) == 0); assert(ptrace(PTRACE_DETACH, pid, 0,0) == 0); assert(pid == waitpid(-1, &stat, 0)); assert(stat == 0x1300); return 0; } Before this patch the child is killed after PTRACE_DETACH. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jan Kratochvil <jan.kratochvil@redhat.com> Cc: Michael Neuling <mikey@neuling.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Mundt <lethal@linux-sh.org> Cc: Will Deacon <will.deacon@arm.com> Cc: Prasad <prasad@linux.vnet.ibm.com> Cc: Russell King <linux@arm.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/ptrace.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index a146ee327f6a..4041f5747e73 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -469,6 +469,7 @@ static int ptrace_detach(struct task_struct *child, unsigned int data)
/* Architecture-specific hardware disable .. */
ptrace_disable(child);
clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
+ flush_ptrace_hw_breakpoint(child);
write_lock_irq(&tasklist_lock);
/*