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4.19.x+fslc
linux-brain/kernel/trace
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Cengiz Can 6d1444dbf9 blktrace: fix dereference after null check 
commit 153031a301bb07194e9c37466cfce8eacb977621 upstream.

There was a recent change in blktrace.c that added a RCU protection to
`q->blk_trace` in order to fix a use-after-free issue during access.

However the change missed an edge case that can lead to dereferencing of
`bt` pointer even when it's NULL:

Coverity static analyzer marked this as a FORWARD_NULL issue with CID
1460458.

```
/kernel/trace/blktrace.c: 1904 in sysfs_blk_trace_attr_store()
1898            ret = 0;
1899            if (bt == NULL)
1900                    ret = blk_trace_setup_queue(q, bdev);
1901
1902            if (ret == 0) {
1903                    if (attr == &dev_attr_act_mask)
>>>     CID 1460458:  Null pointer dereferences  (FORWARD_NULL)
>>>     Dereferencing null pointer "bt".
1904                            bt->act_mask = value;
1905                    else if (attr == &dev_attr_pid)
1906                            bt->pid = value;
1907                    else if (attr == &dev_attr_start_lba)
1908                            bt->start_lba = value;
1909                    else if (attr == &dev_attr_end_lba)
```

Added a reassignment with RCU annotation to fix the issue.

Fixes: c780e86dd48 ("blktrace: Protect q->blk_trace with RCU")
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Bob Liu <bob.liu@oracle.com>
Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Cengiz Can <cengiz@kernel.wtf>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2020-04-29 16:31:17 +02:00
..
blktrace.c blktrace: fix dereference after null check 2020-04-29 16:31:17 +02:00
bpf_trace.c bpf: fix nested bpf tracepoints with per-cpu data 2019-07-03 13:14:48 +02:00
ftrace.c ftrace: fpid_next() should increase position index 2020-02-24 08:34:52 +01:00
Kconfig Masami found an off by one bug in the code that keeps "notrace" functions 2018-08-23 13:07:00 -07:00
Makefile tracing: Allow gcov profiling on only ftrace subsystem 2018-08-21 09:11:49 -04:00
power-traces.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
preemptirq_delay_test.c tracing: Use trace_clock_local() for looping in preemptirq_delay_test.c 2018-10-17 15:35:33 -04:00
ring_buffer_benchmark.c tracing: Add SPDX License format tags to tracing files 2018-08-16 19:08:06 -04:00
ring_buffer.c trace: Fix preempt_enable_no_resched() abuse 2019-05-02 09:58:54 +02:00
rpm-traces.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
trace_benchmark.c rcu: Rename cond_resched_rcu_qs() to cond_resched_tasks_rcu_qs() 2018-05-15 10:27:29 -07:00
trace_benchmark.h tracing: Fix SPDX format headers to use C++ style comments 2018-08-16 19:08:06 -04:00
trace_branch.c Revert "x86/uaccess, ftrace: Fix ftrace_likely_update() vs. SMAP" 2019-07-03 13:14:41 +02:00
trace_clock.c tracing: Add SPDX License format tags to tracing files 2018-08-16 19:08:06 -04:00
trace_entries.h tracing: Fix SPDX format headers to use C++ style comments 2018-08-16 19:08:06 -04:00
trace_event_perf.c tracing: Fix race in perf_trace_buf initialization 2019-10-29 09:20:03 +01:00
trace_events_filter_test.h tracing: Fix SPDX format headers to use C++ style comments 2018-08-16 19:08:06 -04:00
trace_events_filter.c tracing: Avoid memory leak in process_system_preds() 2020-01-09 10:19:02 +01:00
trace_events_hist.c tracing: Fix histogram code when expression has same var as value 2020-01-29 16:43:23 +01:00
trace_events_trigger.c tracing: Fix the race between registering 'snapshot' event trigger and triggering 'snapshot' operation 2020-04-21 09:03:09 +02:00
trace_events.c tracing: Fix lock inversion in trace_event_enable_tgid_record() 2020-01-09 10:19:02 +01:00
trace_export.c tracing: Add trigger file for trace_markers tracefs/ftrace/print 2018-05-29 08:28:53 -04:00
trace_functions_graph.c tracing/fgraph: Fix set_graph_function from showing interrupts 2018-12-08 12:59:07 +01:00
trace_functions.c tracing: Update stack trace skipping for ORC unwinder 2018-01-23 15:57:00 -05:00
trace_hwlat.c tracing/hwlat: Don't ignore outer-loop duration when calculating max_latency 2019-10-17 13:45:39 -07:00
trace_irqsoff.c tracing/fgraph: Fix set_graph_function from showing interrupts 2018-12-08 12:59:07 +01:00
trace_kdb.c tracing: Silence GCC 9 array bounds warning 2019-06-25 11:35:52 +08:00
trace_kprobe_selftest.c selftest/ftrace: Move kprobe selftest function to separate compile unit 2018-07-30 18:41:04 -04:00
trace_kprobe_selftest.h tracing: Fix SPDX format headers to use C++ style comments 2018-08-16 19:08:06 -04:00
trace_kprobe.c ftrace/kprobe: Show the maxactive number on kprobe_events 2020-04-17 10:48:55 +02:00
trace_mmiotrace.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
trace_nop.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
trace_output.c tracing: Add SPDX License format tags to tracing files 2018-08-16 19:08:06 -04:00
trace_output.h tracing: Fix SPDX format headers to use C++ style comments 2018-08-16 19:08:06 -04:00
trace_preemptirq.c tracing: More reverting of "tracing: Centralize preemptirq tracepoints and unify their usage" 2018-08-10 15:12:00 -04:00
trace_printk.c tracing: Add SPDX License format tags to tracing files 2018-08-16 19:08:06 -04:00
trace_probe.c tracing: Add SPDX License format tags to tracing files 2018-08-16 19:08:06 -04:00
trace_probe.h tracing: Add SPDX License format tags to tracing files 2018-08-16 19:08:06 -04:00
trace_sched_switch.c tracing: Fix sched switch start/stop refcount racy updates 2020-02-11 04:33:55 -08:00
trace_sched_wakeup.c kernel/trace: Fix do not unregister tracepoints when register sched_migrate_task fail 2020-01-14 20:06:59 +01:00
trace_selftest_dynamic.c ftrace: Mark function tracer test functions noinline/noclone 2018-01-23 15:57:29 -05:00
trace_selftest.c Tracing updates for 4.15: 2017-11-17 14:58:01 -08:00
trace_seq.c tracing: Add SPDX License format tags to tracing files 2018-08-16 19:08:06 -04:00
trace_stack.c tracing: Have stack tracer compile when MCOUNT_INSN_SIZE is not defined 2020-01-14 20:06:59 +01:00
trace_stat.c tracing: Fix very unlikely race of registering two stat tracers 2020-02-24 08:34:39 +01:00
trace_stat.h tracing: Fix SPDX format headers to use C++ style comments 2018-08-16 19:08:06 -04:00
trace_syscalls.c Tracing updates for 4.15: 2017-11-17 14:58:01 -08:00
trace_uprobe.c tracing/uprobes: Fix output for multiple string arguments 2019-02-20 10:25:48 +01:00
trace.c tracing: Disable trace_printk() on post poned tests 2020-03-05 16:42:18 +01:00
trace.h ftrace: Protect ftrace_graph_hash with ftrace_sync 2020-02-11 04:34:05 -08:00
tracing_map.c tracing: Have the histogram compare functions convert to u64 first 2020-01-09 10:19:02 +01:00
tracing_map.h tracing: Fix SPDX format headers to use C++ style comments 2018-08-16 19:08:06 -04:00