Description

In the Linux kernel, the following vulnerability has been resolved: drm/msm/dpu: Disallow unallocated resources to be returned In the event that the topology requests resources that have not been created by the system (because they are typically not represented in dpu_mdss_cfg ^1), the resource(s) in global_state (in this case DSC blocks, until their allocation/assignment is being sanity-checked in "drm/msm/dpu: Reject topologies for which no DSC blocks are available") remain NULL but will still be returned out of dpu_rm_get_assigned_resources, where the caller expects to get an array containing num_blks valid pointers (but instead gets these NULLs). To prevent this from happening, where null-pointer dereferences typically result in a hard-to-debug platform lockup, num_blks shouldn't increase past NULL blocks and will print an error and break instead. After all, max_blks represents the static size of the maximum number of blocks whereas the actual amount varies per platform. ^1: which can happen after a git rebase ended up moving additions to _dpu_cfg to a different struct which has the same patch context. Patchwork: https://patchwork.freedesktop.org/patch/517636/

References 5

• git.kernel.org https://git.kernel.org/stable/c/8dbd54d679e3ab37be43bc1ed9f463dbf83a2259
• git.kernel.org https://git.kernel.org/stable/c/9e1e236acdc42b5c43ec8d7f03a39537e70cc309
• git.kernel.org https://git.kernel.org/stable/c/9fe3644c720ac87d150f0bba5a4ae86cae55afaf
• git.kernel.org https://git.kernel.org/stable/c/abc40122d9a69f56c04efb5a7485795f5ac799d1
• git.kernel.org https://git.kernel.org/stable/c/bf661c5e3bc48973acb363c76e3db965d9ed26d0

Remediation