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20 lines
2.0 KiB
Markdown
20 lines
2.0 KiB
Markdown
### [CVE-2024-49881](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2024-49881)
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### Description
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In the Linux kernel, the following vulnerability has been resolved:ext4: update orig_path in ext4_find_extent()In ext4_find_extent(), if the path is not big enough, we free it and set*orig_path to NULL. But after reallocating and successfully initializingthe path, we don't update *orig_path, in which case the caller gets avalid path but a NULL ppath, and this may cause a NULL pointer dereferenceor a path memory leak. For example:ext4_split_extent path = *ppath = 2000 ext4_find_extent if (depth > path[0].p_maxdepth) kfree(path = 2000); *orig_path = path = NULL; path = kcalloc() = 3000 ext4_split_extent_at(*ppath = NULL) path = *ppath; ex = path[depth].p_ext; // NULL pointer dereference!==================================================================BUG: kernel NULL pointer dereference, address: 0000000000000010CPU: 6 UID: 0 PID: 576 Comm: fsstress Not tainted 6.11.0-rc2-dirty #847RIP: 0010:ext4_split_extent_at+0x6d/0x560Call Trace: <TASK> ext4_split_extent.isra.0+0xcb/0x1b0 ext4_ext_convert_to_initialized+0x168/0x6c0 ext4_ext_handle_unwritten_extents+0x325/0x4d0 ext4_ext_map_blocks+0x520/0xdb0 ext4_map_blocks+0x2b0/0x690 ext4_iomap_begin+0x20e/0x2c0[...]==================================================================Therefore, *orig_path is updated when the extent lookup succeeds, so thatthe caller can safely use path or *ppath.
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### POC
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#### Reference
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No PoCs from references.
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#### Github
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- https://github.com/w4zu/Debian_security
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