CVE-2026-74400

In the Linux kernel, the following vulnerability has been resolved:

bpf: fix crash in bpf_[set|remove]dentryxattr for negative dentries

bpfsetdentryxattr and bpfremovedentryxattr BPF kfuncs attempt to lock the inode of the supplied dentry without checking if it is NULL. If a negative dentry is passed (e.g. from securityinodecreate), dinode(dentry) returns NULL, and inodelock(inode) will cause a NULL pointer dereference.

Trivially fix this by adding a NULL check for inode before attempting to lock it, returning -EINVAL if it is NULL.

Additionally, drop WARNON(!inode) in bpfxattrreadpermission() and bpfxattrwritepermission(). These warnings could be triggered by passing a negative dentry to bpfgetdentryxattr() or the locked variants of the xattr kfuncs, potentially causing a Denial of Service on systems with panicon_warn enabled. Instead, simply return -EINVAL.