page_pool: Fix PP_MAGIC_MASK to avoid crashing on some 32-bit arches
- Published
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- Fix
- Fixed in 6.12.54, 6.16, 6.17.4
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
- Exploitation: none
- Automatable: no
- Technical impact: total
Summary
In the Linux kernel, the following vulnerability has been resolved: page_pool: Fix PP_MAGIC_MASK to avoid crashing on some 32-bit arches Helge reported that the introduction of PP_MAGIC_MASK let to crashes on boot on his 32-bit parisc machine. The cause of this is the mask is set too wide, so the page_pool_page_is_pp() incurs false positives which crashes the machine. Just disabling the check in page_pool_is_pp() will lead to the page_pool code itself malfunctioning; so instead of doing this, this patch changes the define for PP_DMA_INDEX_BITS to avoid mistaking arbitrary kernel pointers for page_pool-tagged pages. The fix relies on the kernel pointers that alias with the pp_magic field always being above PAGE_OFFSET. With this assumption, we can use the lowest bit of the value of PAGE_OFFSET as the upper bound of the PP_DMA_INDEX_MASK, which should avoid the false positives. Because we cannot rely on PAGE_OFFSET always being a compile-time constant, nor on it always being >0, we fall back to disabling the dma_index storage when there are not enough bits available. This leaves us in the situation we were in before the patch in the Fixes tag, but only on a subset of architecture configurations. This seems to be the best we can do until the transition to page types in complete for page_pool pages. v2: • Make sure there's at least 8 bits available and that the PAGE_OFFSET bit calculation doesn't wrap
Timeline
- CVE published
- CISA SSVC assessment
Exploitation: none · Automatable: no · Technical impact: total
- Record last updated
Affected versions
- Linux Linux
From 4f51fb0d257ff4d406ec27966902de075e3b118e · fixed in 15b8a5b4cdc16e9a8bb2a548e12a0fd92997605a; From ee62ce7a1d909ccba0399680a03c2dee83bcae95 · fixed in f62934cea32c8f7b11b747975d69bf5afe4264cf; From ee62ce7a1d909ccba0399680a03c2dee83bcae95 · fixed in 95920c2ed02bde551ab654e9749c2ca7bc3100e0; From 6.12.34 · fixed in 6.12.54; From 6.15.3 · fixed in 6.16
- Linux Linux
6.16
- KernelLinux
fixed in 6.12.54; From 6.13.0 · fixed in 6.17.4