From: Xiaoqi Zhuang Date: Tue, 21 Oct 2025 08:45:25 +0000 (+0800) Subject: coresight: ETR: Fix ETR buffer use-after-free issue X-Git-Tag: v6.19-rc1~65^2~56^2~14 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=35501ac3c7d40a7bb9568c2f89d6b56beaf9bed3;p=thirdparty%2Fkernel%2Flinux.git coresight: ETR: Fix ETR buffer use-after-free issue 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 Signed-off-by: Suzuki K Poulose Tested-by: Leo Yan Link: https://lore.kernel.org/r/20251021-fix_etr_issue-v3-1-99a2d066fee2@oss.qualcomm.com --- 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);