6.18-stable review patch. If anyone has any objections, please let me know.
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From: Xiaoqi Zhuang xiaoqi.zhuang@oss.qualcomm.com
[ Upstream commit 35501ac3c7d40a7bb9568c2f89d6b56beaf9bed3 ]
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... Signed-off-by: Sasha Levin sashal@kernel.org --- 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 b07fcdb3fe1a8..800be06598c1b 100644 --- a/drivers/hwtracing/coresight/coresight-tmc-etr.c +++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c @@ -1250,6 +1250,13 @@ static struct etr_buf *tmc_etr_get_sysfs_buffer(struct coresight_device *csdev) * with the lock released. */ raw_spin_lock_irqsave(&drvdata->spinlock, flags); + + /* + * If the ETR is already enabled, continue with the existing buffer. + */ + if (coresight_get_mode(csdev) == CS_MODE_SYSFS) + goto out; + sysfs_buf = READ_ONCE(drvdata->sysfs_buf); if (!sysfs_buf || (sysfs_buf->size != drvdata->size)) { raw_spin_unlock_irqrestore(&drvdata->spinlock, flags);