CVE-2026-64264 in Linux
Résumé
par MITRE • 25/07/2026
In the Linux kernel, the following vulnerability has been resolved:
fuse-uring: fix EFAULT clobber in fuse_uring_commit
copy_from_user() returns the number of bytes not copied as an unsigned residual on failure (1..sizeof(struct fuse_out_header)). fuse_uring_commit stores that residual in ssize_t err, sets req->out.h.error to -EFAULT, then jumps to out: with err still holding the positive residual.
err = copy_from_user(&req->out.h, &ent->headers->in_out, sizeof(req->out.h)); if (err) {
req->out.h.error = -EFAULT; goto out; /* err is the positive residual */ } ... out: fuse_uring_req_end(ent, req, err);
fuse_uring_req_end() then runs
if (error) req->out.h.error = error;
which overwrites the just-assigned -EFAULT with the positive residual. FUSE callers such as fuse_simple_request() test err < 0 to detect failure, so the positive value is interpreted as success and the caller proceeds with an uninitialised or partial req->out.args.
Fix by assigning err = -EFAULT in the failure branch before jumping to out, so fuse_uring_req_end() receives a negative errno and sets req->out.h.error to -EFAULT.
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