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Merge: CVE-2022-49648: tracing/histograms: Fix memory leak problem 

MR: https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-9/-/merge_requests/6444

JIRA: https://issues.redhat.com/browse/RHEL-81008
CVE: CVE-2022-49648

```
commit 7edc3945bdce9c39198a10d6129377a5c53559c2
Author: Zheng Yejian <zhengyejian1@huawei.com>
Date:   Mon Jul 11 09:47:31 2022 +0800

    tracing/histograms: Fix memory leak problem

    This reverts commit 46bbe5c671.

    As commit 46bbe5c671 ("tracing: fix double free") said, the
    "double free" problem reported by clang static analyzer is:
      > In parse_var_defs() if there is a problem allocating
      > var_defs.expr, the earlier var_defs.name is freed.
      > This free is duplicated by free_var_defs() which frees
      > the rest of the list.

    However, if there is a problem allocating N-th var_defs.expr:
      + in parse_var_defs(), the freed 'earlier var_defs.name' is
        actually the N-th var_defs.name;
      + then in free_var_defs(), the names from 0th to (N-1)-th are freed;

                            IF ALLOCATING PROBLEM HAPPENED HERE!!! -+
                                                                     \
                                                                      |
              0th           1th                 (N-1)-th      N-th    V
              +-------------+-------------+-----+-------------+-----------
    var_defs: | name | expr | name | expr | ... | name | expr | name | ///
              +-------------+-------------+-----+-------------+-----------

    These two frees don't act on same name, so there was no "double free"
    problem before. Conversely, after that commit, we get a "memory leak"
    problem because the above "N-th var_defs.name" is not freed.

    If enable CONFIG_DEBUG_KMEMLEAK and inject a fault at where the N-th
    var_defs.expr allocated, then execute on shell like:
      $ echo 'hist:key=call_site:val=$v1,$v2:v1=bytes_req,v2=bytes_alloc' > \
    /sys/kernel/debug/tracing/events/kmem/kmalloc/trigger

    Then kmemleak reports:
      unreferenced object 0xffff8fb100ef3518 (size 8):
        comm "bash", pid 196, jiffies 4295681690 (age 28.538s)
        hex dump (first 8 bytes):
          76 31 00 00 b1 8f ff ff                          v1......
        backtrace:
          [<0000000038fe4895>] kstrdup+0x2d/0x60
          [<00000000c99c049a>] event_hist_trigger_parse+0x206f/0x20e0
          [<00000000ae70d2cc>] trigger_process_regex+0xc0/0x110
          [<0000000066737a4c>] event_trigger_write+0x75/0xd0
          [<000000007341e40c>] vfs_write+0xbb/0x2a0
          [<0000000087fde4c2>] ksys_write+0x59/0xd0
          [<00000000581e9cdf>] do_syscall_64+0x3a/0x80
          [<00000000cf3b065c>] entry_SYSCALL_64_after_hwframe+0x46/0xb0

    Link: https://lkml.kernel.org/r/20220711014731.69520-1-zhengyejian1@huawei.com

    Cc: stable@vger.kernel.org
    Fixes: 46bbe5c671 ("tracing: fix double free")
    Reported-by: Hulk Robot <hulkci@huawei.com>
    Suggested-by: Steven Rostedt <rostedt@goodmis.org>
    Reviewed-by: Tom Zanussi <tom.zanussi@linux.intel.com>
    Signed-off-by: Zheng Yejian <zhengyejian1@huawei.com>
    Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>```

Signed-off-by: CKI Backport Bot <cki-ci-bot+cki-gitlab-backport-bot@redhat.com>

---

<small>Created 2025-02-26 22:20 UTC by backporter - [KWF FAQ](https://red.ht/kernel_workflow_doc) - [Slack #team-kernel-workflow](https://redhat-internal.slack.com/archives/C04LRUPMJQ5) - [Source](https://gitlab.com/cki-project/kernel-workflow/-/blob/main/webhook/utils/backporter.py) - [Documentation](https://gitlab.com/cki-project/kernel-workflow/-/blob/main/docs/README.backporter.md) - [Report an issue](https://gitlab.com/cki-project/kernel-workflow/-/issues/new?issue%5Btitle%5D=backporter%20webhook%20issue)</small>

Approved-by: Waiman Long <longman@redhat.com>
Approved-by: Jerome Marchand <jmarchan@redhat.com>
Approved-by: CKI KWF Bot <cki-ci-bot+kwf-gitlab-com@redhat.com>

Merged-by: Augusto Caringi <acaringi@redhat.com>
This commit is contained in:
Augusto Caringi 2025-05-21 18:34:48 -03:00
parent 358f8177c3 b70dedddd5
commit 509e36e98a
1 changed files with 2 additions and 0 deletions
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2
kernel/trace/trace_events_hist.c
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@ -4236,6 +4236,8 @@ static int parse_var_defs(struct hist_trigger_data *hist_data)
s = kstrdup(field_str, GFP_KERNEL);
if (!s) {
kfree(hist_data->attrs->var_defs.name[n_vars]);
hist_data->attrs->var_defs.name[n_vars] = NULL;
ret = -ENOMEM;
goto free;
}