CVE-2026-43303mm/page_alloc: clear page->private in free_pages_prepare()

Official description

In the Linux kernel, the following vulnerability has been resolved: mm/page_alloc: clear page->private in free_pages_prepare() Several subsystems (slub, shmem, ttm, etc.) use page->private but don't clear it before freeing pages. When these pages are later allocated as high-order pages and split via split_page(), tail pages retain stale page->private values. This causes a use-after-free in the swap subsystem. The swap code uses page->private to track swap count continuations, assuming freshly allocated pages have page->private == 0. When stale values are present, swap_count_continued() incorrectly assumes the continuation list is valid and iterates over uninitialized page->lru containing LIST_POISON values, causing a crash: KASAN: maybe wild-memory-access in range [0xdead000000000100-0xdead000000000107] RIP: 0010:__do_sys_swapoff+0x1151/0x1860 Fix this by clearing page->private in free_pages_prepare(), ensuring all freed pages have clean state regardless of previous use.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/e7790ab165713b79b1617ce659742ceb3a859d05
• https://git.kernel.org/stable/c/3edb8ebbf79b9016040e8f3421d723ae3d542b32
• https://git.kernel.org/stable/c/f9719e32a67b4b00b3c9b133e8b5ffa72a26b67b
• https://git.kernel.org/stable/c/23b82b7a26182ad840ae67d390d7ec9771e8c00f
• https://git.kernel.org/stable/c/d757c793853ec5483eb41ec2942c300b8fa720fb
• https://git.kernel.org/stable/c/ac1ea219590c09572ed5992dc233bbf7bb70fef9
• https://cert-portal.siemens.com/productcert/html/ssa-019113.html
• https://cert-portal.siemens.com/productcert/html/ssa-457936.html
• https://cert-portal.siemens.com/productcert/html/ssa-784472.html