CVE-2026-80806

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CVE-2026-80806

Summary: ext4: don't enable DAX on new encrypted files

Details: In the Linux kernel, the following vulnerability has been resolved: ext4: don't enable DAX on new encrypted files Currently, when a new encrypted regular file is created, the call to ext4_set_inode_flags(inode, init=true) in __ext4_new_inode() is made before EXT4_INODE_ENCRYPT is set. As a result, it can set S_DAX if the filesystem is mounted with "-o dax=always". EXT4_INODE_ENCRYPT then actually gets set a bit later in __ext4_new_inode(), when it calls fscrypt_set_context() which calls ext4_set_context(). ext4_set_context() sets EXT4_INODE_ENCRYPT and calls ext4_set_inode_flags(inode, init=false) to set S_ENCRYPTED too. This was intended to clear S_DAX as well. However, this was broken by commit 043546e46dc7 ("fs/ext4: Only change S_DAX on inode load"). This causes data written to the file to bypass encryption, also causing xfstests failures such as generic/548 (when "-o dax=always" is used). Fix this by simplifying the flow by making __ext4_new_inode() set EXT4_INODE_ENCRYPT earlier. This makes it take effect in ext4_set_inode_flags(inode, init=true), making S_DAX never be set. Similarly, make EXT4_STATE_MAY_INLINE_DATA never be set in the first place on new encrypted inodes. Then it doesn't need to be cleared. As a result of these simplifications, ext4_set_context() no longer needs to change inode flags or state when 'handle != NULL'. Remove that too.

References: https://git.kernel.org/stable/c/3392391b363a63ebb531d45318a729b1c998565b, https://git.kernel.org/stable/c/458776af0061afec1014cb3cd0061e282e482e83, https://git.kernel.org/stable/c/5959cad3cfa852ec07bbdaf9c17f4838a94a8e6c, https://git.kernel.org/stable/c/a13f61ba9b2a7a4ff1f140949ccfad23c5313757, https://git.kernel.org/stable/c/add98959b220935b243170214c787bc03044a44d, https://git.kernel.org/stable/c/da32af420d6d466e247c43ac0b829edeac7ae0ad, https://git.kernel.org/stable/c/e27bae352158c007143d5bb50f3af33a177c0a37, https://git.kernel.org/stable/c/ed1cd834da65db127f1c30ff67e78f14825a06c1, https://git.kernel.org/stable/c/f53b325068bca0b238c3e0d2eb7de9b1f2268cab, https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/80xxx/CVE-2026-80806.json, https://nvd.nist.gov/vuln/detail/CVE-2026-80806, https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git