CVE-2026-53401fbdev: omap2: fix use-after-free in omapfb_mmap

Official description

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.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/a1a00f664a409b3412f9e1408c12890cffe50362
• https://git.kernel.org/stable/c/5e10b1747547c3815e90d28166e92144835e065f
• https://git.kernel.org/stable/c/986d5fafb73b8b866651399934b66d690f49135a
• https://git.kernel.org/stable/c/8363c219d88e78daaee5665117a0380442989338
• https://git.kernel.org/stable/c/6eb6ebcc8590007ad59ddccc8b5f9201655b33f8
• https://git.kernel.org/stable/c/7958e67375aa111522086286bba13cfc0816ce8d