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
Metrics
Affected Vendors & Products
| Vendors | Products |
|---|---|
| Linux |
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No data.
No data.
OpenCVE Enrichment is a feature of OpenCVE that uses AI to automatically link vendors and products to CVEs. Learn more on GitHub.
| Vendors | Products |
|---|---|
| Linux |
|
No advisories yet.
Solution
No solution given by the vendor.
Workaround
No workaround given by the vendor.
Thu, 13 Nov 2025 12:15:00 +0000
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threat_severity
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cvssV3_1
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Thu, 13 Nov 2025 10:00:00 +0000
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Linux
Linux linux Kernel |
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| Vendors & Products |
Linux
Linux linux Kernel |
Wed, 12 Nov 2025 22:15:00 +0000
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| Description | 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 | |
| Title | page_pool: Fix PP_MAGIC_MASK to avoid crashing on some 32-bit arches | |
| References |
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MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2025-11-12T21:56:33.510Z
Reserved: 2025-04-16T07:20:57.178Z
Link: CVE-2025-40199
Vulnrichment
No data.
NVD
Status : Awaiting Analysis
Published: 2025-11-12T22:15:47.043
Modified: 2025-11-14T16:42:30.503
Link: CVE-2025-40199
Redhat
OpenCVE Enrichment
Updated: 2025-11-13T09:52:09Z