drm/radeon: fix uninitialized size issue in radeon_vce_cs_parse()

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: drm/radeon: fix uninitialized size issue in radeon_vce_cs_parse() On the off chance that command stream passed from userspace via ioctl() call to radeon_vce_cs_parse() is weirdly crafted and first command to execute is to encode (case 0x03000001), the function in question will attempt to call radeon_vce_cs_reloc() with size argument that has not been properly initialized. Specifically, 'size' will point to 'tmp' variable before the latter had a chance to be assigned any value. Play it safe and init 'tmp' with 0, thus ensuring that radeon_vce_cs_reloc() will catch an early error in cases like these. Found by Linux Verification Center (linuxtesting.org) with static analysis tool SVACE. (cherry picked from commit 2d52de55f9ee7aaee0e09ac443f77855989c6b68)

References

• https://git.kernel.org/stable/c/0effb378ebce52b897f85cd7f828854b8c7cb636
• https://git.kernel.org/stable/c/5b4d9d20fd455a97920cf158dd19163b879cf65d
• https://git.kernel.org/stable/c/9b2da9c673a0da1359a2151f7ce773e2f77d71a9
• https://git.kernel.org/stable/c/78b07dada3f02f77762d0755a96d35f53b02be69
• https://git.kernel.org/stable/c/3ce08215cad55c10a6eeeb33d3583b6cfffe3ab8
• https://git.kernel.org/stable/c/dd1801aa01bba1760357f2a641346ae149686713
• https://git.kernel.org/stable/c/f5e049028124f755283f2c07e7a3708361ed1dc8
• https://git.kernel.org/stable/c/dd8689b52a24807c2d5ce0a17cb26dc87f75235c