This is a note to let you know that I've just added the patch titled
drm/msm/gpu: Fix potential double-free
to the 6.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
drm-msm-gpu-fix-potential-double-free.patch
and it can be found in the queue-6.1 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit f4b7352857b7dbb86c6a13611c38044dabeaf866
Author: Rob Clark <robdclark@xxxxxxxxxxxx>
Date: Tue Jan 10 13:28:59 2023 -0800
drm/msm/gpu: Fix potential double-free
[ Upstream commit a66f1efcf748febea7758c4c3c8b5bc5294949ef ]
If userspace was calling the MSM_SET_PARAM ioctl on multiple threads to
set the COMM or CMDLINE param, it could trigger a race causing the
previous value to be kfree'd multiple times. Fix this by serializing on
the gpu lock.
Signed-off-by: Rob Clark <robdclark@xxxxxxxxxxxx>
Fixes: d4726d770068 ("drm/msm: Add a way to override processes comm/cmdline")
Patchwork: https://patchwork.freedesktop.org/patch/517778/
Link: https://lore.kernel.org/r/20230110212903.1925878-1-robdclark@xxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/gpu/drm/msm/adreno/adreno_gpu.c b/drivers/gpu/drm/msm/adreno/adreno_gpu.c
index 5a0e8491cd3a..2e7531d2a5d6 100644
--- a/drivers/gpu/drm/msm/adreno/adreno_gpu.c
+++ b/drivers/gpu/drm/msm/adreno/adreno_gpu.c
@@ -351,6 +351,8 @@ int adreno_set_param(struct msm_gpu *gpu, struct msm_file_private *ctx,
/* Ensure string is null terminated: */
str[len] = '\0';
+ mutex_lock(&gpu->lock);
+
if (param == MSM_PARAM_COMM) {
paramp = &ctx->comm;
} else {
@@ -360,6 +362,8 @@ int adreno_set_param(struct msm_gpu *gpu, struct msm_file_private *ctx,
kfree(*paramp);
*paramp = str;
+ mutex_unlock(&gpu->lock);
+
return 0;
}
case MSM_PARAM_SYSPROF:
diff --git a/drivers/gpu/drm/msm/msm_gpu.c b/drivers/gpu/drm/msm/msm_gpu.c
index 021f4e29b613..4f495eecc34b 100644
--- a/drivers/gpu/drm/msm/msm_gpu.c
+++ b/drivers/gpu/drm/msm/msm_gpu.c
@@ -335,6 +335,8 @@ static void get_comm_cmdline(struct msm_gem_submit *submit, char **comm, char **
struct msm_file_private *ctx = submit->queue->ctx;
struct task_struct *task;
+ WARN_ON(!mutex_is_locked(&submit->gpu->lock));
+
/* Note that kstrdup will return NULL if argument is NULL: */
*comm = kstrdup(ctx->comm, GFP_KERNEL);
*cmd = kstrdup(ctx->cmdline, GFP_KERNEL);
diff --git a/drivers/gpu/drm/msm/msm_gpu.h b/drivers/gpu/drm/msm/msm_gpu.h
index 58a72e6b1400..a89bfdc3d7f9 100644
--- a/drivers/gpu/drm/msm/msm_gpu.h
+++ b/drivers/gpu/drm/msm/msm_gpu.h
@@ -366,10 +366,18 @@ struct msm_file_private {
*/
int sysprof;
- /** comm: Overridden task comm, see MSM_PARAM_COMM */
+ /**
+ * comm: Overridden task comm, see MSM_PARAM_COMM
+ *
+ * Accessed under msm_gpu::lock
+ */
char *comm;
- /** cmdline: Overridden task cmdline, see MSM_PARAM_CMDLINE */
+ /**
+ * cmdline: Overridden task cmdline, see MSM_PARAM_CMDLINE
+ *
+ * Accessed under msm_gpu::lock
+ */
char *cmdline;
/**
