CVE-2021-47305

In the Linux kernel, the following vulnerability has been resolved:

dma-buf/sync_file: Dont leak fences on merge failure

Each add_fence() call does a dma_fence_get() on the relevant fence. In the error path, we werent calling dma_fence_put() so all those fences got leaked. Also, in the krealloc_array failure case, we werent freeing the fences array. Instead, ensure that i and fences are always zero-initialized and dma_fence_put() all the fences and kfree(fences) on every error path.

Weakness

The product contains an assert() or similar statement that can be triggered by an attacker, which leads to an application exit or other behavior that is more severe than necessary.

Affected Software

Extended Description

While assertion is good for catching logic errors and reducing the chances of reaching more serious vulnerability conditions, it can still lead to a denial of service. For example, if a server handles multiple simultaneous connections, and an assert() occurs in one single connection that causes all other connections to be dropped, this is a reachable assertion that leads to a denial of service.

Potential Mitigations

References

• https://git.kernel.org/stable/c/0d514185ae792d3a1903c8e1a83899aa996705ce
• https://git.kernel.org/stable/c/19edcd97727aae9362444a859a24d99a8730cb27
• https://git.kernel.org/stable/c/19f51c2529339280d2c8c6427cd3e21ddf1ac3f8
• https://git.kernel.org/stable/c/41f45e91c92c8480242ea448d54e28c753b13902
• https://git.kernel.org/stable/c/e0355a0ad31a1d677b2a4514206de4902bd550e8
• https://git.kernel.org/stable/c/ffe000217c5068c5da07ccb1c0f8cce7ad767435
• https://git.kernel.org/stable/c/0d514185ae792d3a1903c8e1a83899aa996705ce
• https://git.kernel.org/stable/c/19edcd97727aae9362444a859a24d99a8730cb27
• https://git.kernel.org/stable/c/19f51c2529339280d2c8c6427cd3e21ddf1ac3f8
• https://git.kernel.org/stable/c/41f45e91c92c8480242ea448d54e28c753b13902
• https://git.kernel.org/stable/c/e0355a0ad31a1d677b2a4514206de4902bd550e8
• https://git.kernel.org/stable/c/ffe000217c5068c5da07ccb1c0f8cce7ad767435