cbcvebase.
CVE-2024-50250
published 2024-11-09

CVE-2024-50250: In the Linux kernel, the following vulnerability has been resolved: fsdax: dax_unshare_iter needs to copy entire blocks The code that copies data from srcmap…

PriorityP431high7.1CVSS 3.1
AVLACLPRLUINSUCHIHAN
EPSS
0.22%
12.9th percentile
In the Linux kernel, the following vulnerability has been resolved: fsdax: dax_unshare_iter needs to copy entire blocks The code that copies data from srcmap to iomap in dax_unshare_iter is very very broken, which bfoster's recent fsx changes have exposed. If the pos and len passed to dax_file_unshare are not aligned to an fsblock boundary, the iter pos and length in the _iter function will reflect this unalignment. dax_iomap_direct_access always returns a pointer to the start of the kmapped fsdax page, even if its pos argument is in the middle of that page. This is catastrophic for data integrity when iter->pos is not aligned to a page, because daddr/saddr do not point to the same byte in the file as iter->pos. Hence we corrupt user data by copying it to the wrong place. If iter->pos + iomap_length() in the _iter function not aligned to a page, then we fail to copy a full block, and only partially populate the destination block. This is catastrophic for data confidentiality because we expose stale pmem contents. Fix both of these issues by aligning copy_pos/copy_len to a page boundary (remember, this is fsdax so 1 fsblock == 1 base page) so that we always copy full blocks. We're not done yet -- there's no call to invalidate_inode_pages2_range, so programs that have the file range mmap'd will continue accessing the old memory mapping after the file metadata updates have completed. Be careful with the return value -- if the unshare succeeds, we still need to return the number of bytes that the iomap iter thinks we're operating on.

Affected

19 ranges
VendorProductVersion rangeFixed in
debianlinux< linux 6.1.119-1 (bookworm)linux 6.1.119-1 (bookworm)
debianlinux-6.1< linux 6.1.119-1 (bookworm)linux 6.1.119-1 (bookworm)
linuxlinux
linuxlinux>= 1bec6782a25c9b92c203ea7a1b3e3dc6a468cbc4 < bdbc96c23197d773a7d1bf03e4f11de593b0ff28bdbc96c23197d773a7d1bf03e4f11de593b0ff28
linuxlinux>= 6.1.113 < 6.1.1166.1.116
linuxlinux>= d984648e428bf88cbd94ebe346c73632cb92fffb < 9bc18bb476e50e32e5d08f2734d63d63e0fa528c9bc18bb476e50e32e5d08f2734d63d63e0fa528c
linuxlinux>= d984648e428bf88cbd94ebe346c73632cb92fffb < 8e9c0f500b42216ef930f5c0d1703989a451913d8e9c0f500b42216ef930f5c0d1703989a451913d
linuxlinux>= d984648e428bf88cbd94ebe346c73632cb92fffb < 50793801fc7f6d08def48754fb0f0706b0cfc39450793801fc7f6d08def48754fb0f0706b0cfc394
linuxlinux_kernel
linuxlinux_kernel>= 0 < 6.1.119-16.1.119-1
linuxlinux_kernel>= 0 < 6.11.7-16.11.7-1
linuxlinux_kernel>= 0 < 6.11.7-16.11.7-1
linuxlinux_kernel>= 0 < 6.8.0-58.606.8.0-58.60
linuxlinux_kernel>= 0 < 6.11.0-18.186.11.0-18.18
linuxlinux_kernel>= 6.1.113 < 6.1.1166.1.116
linuxlinux_kernel>= 6.2 < 6.6.606.6.60
linuxlinux_kernel>= 6.7 < 6.11.76.11.7
msrcazl3_kernel_6.6.57.1-7_on_azure_linux_3.0
msrcazl3_kernel_6.6.64.2-1_on_azure_linux_3.0

CVSS provenance

nvdv3.17.1HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
osv8.8HIGH
vendor_ubuntu8.8HIGH
vendor_debian7.1HIGH
vendor_msrc7.1HIGH
vendor_redhat7.1HIGH
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