6.18-stable review patch. If anyone has any objections, please let me know.
------------------
From: Akash Goel akash.goel@arm.com
[ Upstream commit eec7e23d848d2194dd8791fcd0f4a54d4378eecd ]
This commit prevents the possibility of a use after free issue in the GROUP_CREATE ioctl function, which arose as pointer to the group is accessed in that ioctl function after storing it in the Xarray. A malicious userspace can second guess the handle of a group and try to call GROUP_DESTROY ioctl from another thread around the same time as GROUP_CREATE ioctl.
To prevent the use after free exploit, this commit uses a mark on an entry of group pool Xarray which is added just before returning from the GROUP_CREATE ioctl function. The mark is checked for all ioctls that specify the group handle and so userspace won't be abe to delete a group that isn't marked yet.
v2: Add R-bs and fixes tags
Fixes: de85488138247 ("drm/panthor: Add the scheduler logical block") Co-developed-by: Boris Brezillon boris.brezillon@collabora.com Signed-off-by: Boris Brezillon boris.brezillon@collabora.com Signed-off-by: Akash Goel akash.goel@arm.com Reviewed-by: Boris Brezillon boris.brezillon@collabora.com Reviewed-by: Steven Price steven.price@arm.com Reviewed-by: Chia-I Wu olvaffe@gmail.com Link: https://patch.msgid.link/20251127164912.3788155-1-akash.goel@arm.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/gpu/drm/panthor/panthor_sched.c | 19 +++++++++++++++---- 1 file changed, 15 insertions(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/panthor/panthor_sched.c b/drivers/gpu/drm/panthor/panthor_sched.c index 0279e19aadae9..881a07ffbabc8 100644 --- a/drivers/gpu/drm/panthor/panthor_sched.c +++ b/drivers/gpu/drm/panthor/panthor_sched.c @@ -772,6 +772,12 @@ struct panthor_job_profiling_data { */ #define MAX_GROUPS_PER_POOL 128
+/* + * Mark added on an entry of group pool Xarray to identify if the group has + * been fully initialized and can be accessed elsewhere in the driver code. + */ +#define GROUP_REGISTERED XA_MARK_1 + /** * struct panthor_group_pool - Group pool * @@ -2900,7 +2906,7 @@ void panthor_fdinfo_gather_group_samples(struct panthor_file *pfile) return;
xa_lock(&gpool->xa); - xa_for_each(&gpool->xa, i, group) { + xa_for_each_marked(&gpool->xa, i, group, GROUP_REGISTERED) { guard(spinlock)(&group->fdinfo.lock); pfile->stats.cycles += group->fdinfo.data.cycles; pfile->stats.time += group->fdinfo.data.time; @@ -3575,6 +3581,8 @@ int panthor_group_create(struct panthor_file *pfile,
group_init_task_info(group);
+ xa_set_mark(&gpool->xa, gid, GROUP_REGISTERED); + return gid;
err_put_group: @@ -3589,6 +3597,9 @@ int panthor_group_destroy(struct panthor_file *pfile, u32 group_handle) struct panthor_scheduler *sched = ptdev->scheduler; struct panthor_group *group;
+ if (!xa_get_mark(&gpool->xa, group_handle, GROUP_REGISTERED)) + return -EINVAL; + group = xa_erase(&gpool->xa, group_handle); if (!group) return -EINVAL; @@ -3614,12 +3625,12 @@ int panthor_group_destroy(struct panthor_file *pfile, u32 group_handle) }
static struct panthor_group *group_from_handle(struct panthor_group_pool *pool, - u32 group_handle) + unsigned long group_handle) { struct panthor_group *group;
xa_lock(&pool->xa); - group = group_get(xa_load(&pool->xa, group_handle)); + group = group_get(xa_find(&pool->xa, &group_handle, group_handle, GROUP_REGISTERED)); xa_unlock(&pool->xa);
return group; @@ -3706,7 +3717,7 @@ panthor_fdinfo_gather_group_mem_info(struct panthor_file *pfile, return;
xa_lock(&gpool->xa); - xa_for_each(&gpool->xa, i, group) { + xa_for_each_marked(&gpool->xa, i, group, GROUP_REGISTERED) { stats->resident += group->fdinfo.kbo_sizes; if (group->csg_id >= 0) stats->active += group->fdinfo.kbo_sizes;