From: Xiaoqi Zhuang <xiaoqi.zhuang@oss.qualcomm.com> mainline inclusion from mainline-v6.19-rc1 commit 35501ac3c7d40a7bb9568c2f89d6b56beaf9bed3 category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/12741 CVE: CVE-2025-68376 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- When ETR is enabled as CS_MODE_SYSFS, if the buffer size is changed and enabled again, currently sysfs_buf will point to the newly allocated memory(buf_new) and free the old memory(buf_old). But the etr_buf that is being used by the ETR remains pointed to buf_old, not updated to buf_new. In this case, it will result in a memory use-after-free issue. Fix this by checking ETR's mode before updating and releasing buf_old, if the mode is CS_MODE_SYSFS, then skip updating and releasing it. Fixes: bd2767ec3df2 ("coresight: Fix run time warnings while reusing ETR buffer") Signed-off-by: Xiaoqi Zhuang <xiaoqi.zhuang@oss.qualcomm.com> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> Tested-by: Leo Yan <leo.yan@arm.com> Link: https://lore.kernel.org/r/20251021-fix_etr_issue-v3-1-99a2d066fee2@oss.qualc... Conflicts: drivers/hwtracing/coresight/coresight-tmc-etr.c [Context conflicts.] Signed-off-by: Hongbo Li <lihongbo22@huawei.com> --- drivers/hwtracing/coresight/coresight-tmc-etr.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c index f3312fbcdc0f..e9b8a396e4ba 100644 --- a/drivers/hwtracing/coresight/coresight-tmc-etr.c +++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c @@ -1156,6 +1156,13 @@ static struct etr_buf *tmc_etr_get_sysfs_buffer(struct coresight_device *csdev) * with the lock released. */ spin_lock_irqsave(&drvdata->spinlock, flags); + + /* + * If the ETR is already enabled, continue with the existing buffer. + */ + if (drvdata->mode == CS_MODE_SYSFS) + goto out; + sysfs_buf = READ_ONCE(drvdata->sysfs_buf); if (!sysfs_buf || (sysfs_buf->size != drvdata->size)) { spin_unlock_irqrestore(&drvdata->spinlock, flags); -- 2.34.1