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Groups > linux.kernel > #1738462
| From | Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | [PATCH 4.9 56/77] tracing: Add barrier to trace_printk() buffer nesting modification |
| Date | 2017-09-24 23:10 +0200 |
| Message-ID | <utmk1-5jg-1@gated-at.bofh.it> (permalink) |
| References | <utlQZ-4Ti-7@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
4.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Steven Rostedt (VMware) <rostedt@goodmis.org>
commit 3d9622c12c8873911f4cc0ccdabd0362c2fca06b upstream.
trace_printk() uses 4 buffers, one for each context (normal, softirq, irq
and NMI), such that it does not need to worry about one context preempting
the other. There's a nesting counter that gets incremented to figure out
which buffer to use. If the context gets preempted by another context which
calls trace_printk() it will increment the counter and use the next buffer,
and restore the counter when it is finished.
The problem is that gcc may optimize the modification of the buffer nesting
counter and it may not be incremented in memory before the buffer is used.
If this happens, and the context gets interrupted by another context, it
could pick the same buffer and corrupt the one that is being used.
Compiler barriers need to be added after the nesting variable is incremented
and before it is decremented to prevent usage of the context buffers by more
than one context at the same time.
Cc: Andy Lutomirski <luto@kernel.org>
Fixes: e2ace00117 ("tracing: Choose static tp_printk buffer by explicit nesting count")
Hat-tip-to: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
kernel/trace/trace.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2369,11 +2369,17 @@ static char *get_trace_buf(void)
if (!buffer || buffer->nesting >= 4)
return NULL;
- return &buffer->buffer[buffer->nesting++][0];
+ buffer->nesting++;
+
+ /* Interrupts must see nesting incremented before we use the buffer */
+ barrier();
+ return &buffer->buffer[buffer->nesting][0];
}
static void put_trace_buf(void)
{
+ /* Don't let the decrement of nesting leak before this */
+ barrier();
this_cpu_dec(trace_percpu_buffer->nesting);
}
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[PATCH 4.9 00/77] 4.9.52-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 22:40 +0200
[PATCH 4.9 60/77] PCI: pciehp: Report power fault only once until we clear it Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 22:40 +0200
[PATCH 4.9 30/77] powerpc: Fix DAR reporting when alignment handler faults Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 22:40 +0200
[PATCH 4.9 55/77] ftrace: Fix memleak when unregistering dynamic ops when tracing disabled Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 22:40 +0200
[PATCH 4.9 42/77] scsi: zfcp: trace high part of "new" 64 bit SCSI LUN Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 22:40 +0200
[PATCH 4.9 54/77] ftrace: Fix selftest goto location on error Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 22:40 +0200
[PATCH 4.9 75/77] mac80211_hwsim: Use proper TX power Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 22:40 +0200
[PATCH 4.9 21/77] MIPS: math-emu: <MADDF|MSUBF>.<D|S>: Fix some cases of infinite inputs Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 22:40 +0200
[PATCH 4.9 27/77] [PATCH - RESEND] crypto: AF_ALG - remove SGL terminator indicator when chaining Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 22:40 +0200
[PATCH 4.9 04/77] orangefs: Dont clear SGID when inheriting ACLs Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 22:40 +0200
[PATCH 4.9 06/77] drm/sun4i: Implement drm_driver lastclose to restore fbdev console Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 22:40 +0200
[PATCH 4.9 44/77] scsi: megaraid_sas: Check valid aen class range to avoid kernel panic Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 22:40 +0200
[PATCH 4.9 63/77] s390/mm: fix race on mm->context.flush_mm Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 22:50 +0200
[PATCH 4.9 65/77] media: uvcvideo: Prevent heap overflow when accessing mapped controls Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 22:50 +0200
[PATCH 4.9 67/77] bcache: initialize dirty stripes in flash_dev_run() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 22:50 +0200
[PATCH 4.9 61/77] net/netfilter/nf_conntrack_core: Fix net_conntrack_lock() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 22:50 +0200
[PATCH 4.9 56/77] tracing: Add barrier to trace_printk() buffer nesting modification Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:10 +0200
[PATCH 4.9 68/77] bcache: Fix leak of bdev reference Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:10 +0200
[PATCH 4.9 24/77] MIPS: math-emu: <MADDF|MSUBF>.S: Fix accuracy (32-bit case) Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:10 +0200
[PATCH 4.9 74/77] mac80211: fix VLAN handling with TXQs Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:10 +0200
[PATCH 4.9 59/77] PCI: shpchp: Enable bridge bus mastering if MSI is enabled Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:10 +0200
[PATCH 4.9 58/77] ARC: Re-enable MMU upon Machine Check exception Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:10 +0200
[PATCH 4.9 26/77] crypto: ccp - Fix XTS-AES-128 support on v5 CCPs Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:10 +0200
[PATCH 4.9 66/77] PM / devfreq: Fix memory leak when fail to register device Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:10 +0200
[PATCH 4.9 64/77] media: v4l2-compat-ioctl32: Fix timespec conversion Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:10 +0200
[PATCH 4.9 69/77] bcache: do not subtract sectors_to_gc for bypassed IO Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:10 +0200
[PATCH 4.9 73/77] bcache: fix bch_hprint crash and improve output Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:10 +0200
[PATCH 4.9 62/77] s390/mm: fix local TLB flushing vs. detach of an mm address space Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:10 +0200
[PATCH 4.9 57/77] tracing: Apply trace_clock changes to instance max buffer Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:10 +0200
[PATCH 4.9 18/77] MIPS: math-emu: MINA.<D|S>: Fix some cases of infinity and zero inputs Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:10 +0200
[PATCH 4.9 76/77] mac80211: flush hw_roc_start work before cancelling the ROC Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:10 +0200
[PATCH 4.9 39/77] scsi: zfcp: fix missing trace records for early returns in TMF eh handlers Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:20 +0200
[PATCH 4.9 40/77] scsi: zfcp: fix payload with full FCP_RSP IU in SCSI trace records Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:20 +0200
[PATCH 4.9 41/77] scsi: zfcp: trace HBA FSF response by default on dismiss or timedout late response Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:20 +0200
[PATCH 4.9 34/77] skd: Submit requests to firmware before triggering the doorbell Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:20 +0200
[PATCH 4.9 33/77] skd: Avoid that module unloading triggers a use-after-free Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:20 +0200
[PATCH 4.9 50/77] scsi: sg: factor out sg_fill_request_table() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:20 +0200
[PATCH 4.9 11/77] pinctrl/amd: save pin registers over suspend/resume Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:20 +0200
[PATCH 4.9 48/77] scsi: sg: use standard lists for sg_requests Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:20 +0200
[PATCH 4.9 03/77] mm: prevent double decrease of nr_reserved_highatomic Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:20 +0200
[PATCH 4.9 35/77] scsi: zfcp: fix queuecommand for scsi_eh commands when DIX enabled Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:20 +0200
[PATCH 4.9 47/77] scsi: sg: remove save_scat_len Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:20 +0200
[PATCH 4.9 17/77] MIPS: math-emu: <MAXA|MINA>.<D|S>: Fix cases of both infinite inputs Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:20 +0200
[PATCH 4.9 45/77] scsi: megaraid_sas: Return pended IOCTLs with cmd_status MFI_STAT_WRONG_STATE in case adapter is dead Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:20 +0200
[PATCH 4.9 31/77] block: Relax a check in blk_start_queue() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:20 +0200
[PATCH 4.9 53/77] scsi: qla2xxx: Fix an integer overflow in sysfs code Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:20 +0200
[PATCH 4.9 10/77] tty: fix __tty_insert_flip_char regression Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:20 +0200
[PATCH 4.9 29/77] ext4: fix quota inconsistency during orphan cleanup for read-only mounts Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:20 +0200
[PATCH 4.9 43/77] scsi: megaraid_sas: set minimum value of resetwaittime to be 1 secs Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:20 +0200
[PATCH 4.9 12/77] Input: i8042 - add Gigabyte P57 to the keyboard reset table Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:20 +0200
[PATCH 4.9 16/77] MIPS: math-emu: <MAXA|MINA>.<D|S>: Fix cases of input values with opposite signs Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:20 +0200
[PATCH 4.9 15/77] MIPS: math-emu: <MAX|MIN>.<D|S>: Fix cases of both inputs negative Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:20 +0200
[PATCH 4.9 07/77] IB/addr: Fix setting source address in addr6_resolve() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:20 +0200
[PATCH 4.9 09/77] tty: improve tty_insert_flip_char() slow path Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:20 +0200
[PATCH 4.9 19/77] MIPS: math-emu: Handle zero accumulator case in MADDF and MSUBF separately Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:20 +0200
[PATCH 4.9 51/77] scsi: sg: fixup infoleak when using SG_GET_REQUEST_TABLE Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:20 +0200
[PATCH 4.9 28/77] ext4: fix incorrect quotaoff if the quota feature is enabled Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:20 +0200
[PATCH 4.9 05/77] IB/{qib, hfi1}: Avoid flow control testing for RDMA write operation Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:20 +0200
[PATCH 4.9 20/77] MIPS: math-emu: <MADDF|MSUBF>.<D|S>: Fix NaN propagation Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:20 +0200
Re: [PATCH 4.9 00/77] 4.9.52-stable review Guenter Roeck <linux@roeck-us.net> - 2017-09-25 03:10 +0200
Re: [PATCH 4.9 00/77] 4.9.52-stable review Tom Gall <tom.gall@linaro.org> - 2017-09-25 06:40 +0200
Re: [PATCH 4.9 00/77] 4.9.52-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-25 08:30 +0200
Re: [PATCH 4.9 00/77] 4.9.52-stable review Shuah Khan <shuahkh@osg.samsung.com> - 2017-09-26 01:20 +0200
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