The patch titled
Subject: ptrace/x86: revert "hw_breakpoints: Fix racy access to ptrace breakpoints"
has been added to the -mm tree. Its filename is
ptrace-x86-revert-hw_breakpoints-fix-racy-access-to-ptrace-breakpoints.patch
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------------------------------------------------------
From: Oleg Nesterov <oleg@xxxxxxxxxx>
Subject: ptrace/x86: revert "hw_breakpoints: Fix racy access to ptrace breakpoints"
This reverts commit 87dc669ba257 ("hw_breakpoints: Fix racy access to
ptrace breakpoints").
The patch was fine but we can no longer race with SIGKILL after 9899d11f
("ptrace: ensure arch_ptrace/ptrace_request can never race with SIGKILL"),
the __TASK_TRACED tracee can't be woken up and ->ptrace_bps[] can't go
away.
The patch only removes ptrace_get_breakpoints/ptrace_put_breakpoints and
does a couple of "while at it" cleanups, it doesn't remove other changes
from the reverted commit.
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Acked-by: Ingo Molnar <mingo@xxxxxxxxxx>
Acked-by: Frederic Weisbecker <fweisbec@xxxxxxxxx>
Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Cc: Jan Kratochvil <jan.kratochvil@xxxxxxxxxx>
Cc: Michael Neuling <mikey@xxxxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Paul Mundt <lethal@xxxxxxxxxxxx>
Cc: Will Deacon <will.deacon@xxxxxxx>
Cc: Prasad <prasad@xxxxxxxxxxxxxxxxxx>
Cc: Russell King <linux@xxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/x86/kernel/ptrace.c | 28 +++++-----------------------
1 file changed, 5 insertions(+), 23 deletions(-)
diff -puN arch/x86/kernel/ptrace.c~ptrace-x86-revert-hw_breakpoints-fix-racy-access-to-ptrace-breakpoints arch/x86/kernel/ptrace.c
--- a/arch/x86/kernel/ptrace.c~ptrace-x86-revert-hw_breakpoints-fix-racy-access-to-ptrace-breakpoints
+++ a/arch/x86/kernel/ptrace.c
@@ -641,9 +641,6 @@ static int ptrace_write_dr7(struct task_
unsigned len, type;
struct perf_event *bp;
- if (ptrace_get_breakpoints(tsk) < 0)
- return -ESRCH;
-
data &= ~DR_CONTROL_RESERVED;
old_dr7 = ptrace_get_dr7(thread->ptrace_bps);
restore:
@@ -692,9 +689,7 @@ restore:
goto restore;
}
- ptrace_put_breakpoints(tsk);
-
- return ((orig_ret < 0) ? orig_ret : rc);
+ return orig_ret < 0 ? orig_ret : rc;
}
/*
@@ -706,18 +701,10 @@ static unsigned long ptrace_get_debugreg
unsigned long val = 0;
if (n < HBP_NUM) {
- struct perf_event *bp;
-
- if (ptrace_get_breakpoints(tsk) < 0)
- return -ESRCH;
+ struct perf_event *bp = thread->ptrace_bps[n];
- bp = thread->ptrace_bps[n];
- if (!bp)
- val = 0;
- else
+ if (bp)
val = bp->hw.info.address;
-
- ptrace_put_breakpoints(tsk);
} else if (n == 6) {
val = thread->debugreg6;
} else if (n == 7) {
@@ -734,9 +721,6 @@ static int ptrace_set_breakpoint_addr(st
struct perf_event_attr attr;
int err = 0;
- if (ptrace_get_breakpoints(tsk) < 0)
- return -ESRCH;
-
if (!t->ptrace_bps[nr]) {
ptrace_breakpoint_init(&attr);
/*
@@ -762,7 +746,7 @@ static int ptrace_set_breakpoint_addr(st
*/
if (IS_ERR(bp)) {
err = PTR_ERR(bp);
- goto put;
+ goto out;
}
t->ptrace_bps[nr] = bp;
@@ -773,9 +757,7 @@ static int ptrace_set_breakpoint_addr(st
attr.bp_addr = addr;
err = modify_user_hw_breakpoint(bp, &attr);
}
-
-put:
- ptrace_put_breakpoints(tsk);
+out:
return err;
}
_
Patches currently in -mm which might be from oleg@xxxxxxxxxx are
posix_cpu_timer-consolidate-expiry-time-type.patch
posix_cpu_timers-consolidate-timer-list-cleanups.patch
posix_cpu_timers-consolidate-expired-timers-check.patch
posix-timers-correctly-get-dying-task-time-sample-in-posix_cpu_timer_schedule.patch
posix_timers-fix-racy-timer-delta-caching-on-task-exit.patch
lockdep-introduce-lock_acquire_exclusive-shared-helper-macros.patch
lglock-update-lockdep-annotations-to-report-recursive-local-locks.patch
autofs4-allow-autofs-to-work-outside-the-initial-pid-namespace.patch
autofs4-translate-pids-to-the-right-namespace-for-the-daemon.patch
ptrace-x86-revert-hw_breakpoints-fix-racy-access-to-ptrace-breakpoints.patch
ptrace-powerpc-revert-hw_breakpoints-fix-racy-access-to-ptrace-breakpoints.patch
ptrace-arm-revert-hw_breakpoints-fix-racy-access-to-ptrace-breakpoints.patch
ptrace-sh-revert-hw_breakpoints-fix-racy-access-to-ptrace-breakpoints.patch
ptrace-revert-prepare-to-fix-racy-accesses-on-task-breakpoints.patch
ptrace-x86-simplify-the-disable-logic-in-ptrace_write_dr7.patch
ptrace-x86-dont-delay-disable-till-second-pass-in-ptrace_write_dr7.patch
ptrace-x86-introduce-ptrace_register_breakpoint.patch
ptrace-x86-ptrace_write_dr7-should-create-bp-if-disabled.patch
ptrace-x86-cleanup-ptrace_set_debugreg.patch
ptrace-ptrace_detach-should-do-flush_ptrace_hw_breakpointchild.patch
ptrace-x86-flush_ptrace_hw_breakpoint-shoule-clear-the-virtual-debug-registers.patch
x86-kill-tif_debug.patch
--
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