Linux kernel fbdev OMAP2 UAF in omapfb_mmap() via OMAPFB_SETUP_PLANE race
CVE-2026-53401 Published on July 19, 2026
fbdev: omap2: fix use-after-free in omapfb_mmap
In the Linux kernel, the following vulnerability has been resolved:
fbdev: omap2: fix use-after-free in omapfb_mmap
omapfb_mmap() has a race condition with OMAPFB_SETUP_PLANE ioctl that
can lead to use-after-free:
The fb_mmap() entry point holds mm_lock but not lock (fb_info->lock),
while ioctl handlers like OMAPFB_SETUP_PLANE hold lock but not mm_lock.
This allows concurrent execution.
In omapfb_mmap():
1. rg = omapfb_get_mem_region(ofbi->region); // Get old region ref
2. start = omapfb_get_region_paddr(ofbi); // Read from NEW region
3. len = fix->smem_len; // Read from NEW region
4. vm_iomap_memory(vma, start, len); // Map NEW region memory
5. atomic_inc(&rg->map_count); // Increment OLD region!
Concurrently, OMAPFB_SETUP_PLANE can:
- Reassign ofbi->region = new_rg
- Update fix->smem_len
- OMAPFB_SETUP_MEM then checks NEW region's map_count (0!) and frees it
This leaves userspace with a mapping to freed physical memory.
The fix is to read all required values (start, len) from the same
region reference (rg) that will have its map_count incremented,
preventing the region from being freed while still mapped.
Products Associated with CVE-2026-53401
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Affected Versions
Linux:- Version 078ff546a806b2c2ab74c25c8edd4c6d4680656a and below 6eb6ebcc8590007ad59ddccc8b5f9201655b33f8 is affected.
- Version 078ff546a806b2c2ab74c25c8edd4c6d4680656a and below 7958e67375aa111522086286bba13cfc0816ce8d is affected.
- Version 2.6.36 is affected.
- Before 2.6.36 is unaffected.
- Version 7.1.3, <= 7.1.* is unaffected.
- Version 7.2, <= * is unaffected.
Exploit Probability
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