CVE-2026-64317

Summary

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

isofs: bound Rock Ridge symlink components to the SL record

get_symlink_chunk() and the SL handling in parse_rock_ridge_inode_internal() walk the variable-length components of a Rock Ridge "SL" (symbolic link) record. Each component is a two-byte header (flags, len) followed by len bytes of text, so it occupies slp->len + 2 bytes. Both loops read slp->len and advance to the next component, and get_symlink_chunk() additionally does memcpy(rpnt, slp->text, slp->len), but neither checks that the component lies within the SL record before dereferencing it.

A crafted SL record whose component declares a len that runs past the record (rr->len) therefore triggers an out-of-bounds read of up to 255 bytes. When the record sits at the tail of its backing buffer - for example a small kmalloc()ed continuation block reached through a CE record - the read crosses the allocation; get_symlink_chunk() then copies the out-of-bounds bytes into the symlink body returned to user space by readlink(), disclosing adjacent kernel memory.

ISO 9660 images are routinely mounted from untrusted removable media - desktop environments auto-mount them (e.g. via udisks2) without CAP_SYS_ADMIN - so the record contents are attacker-controlled.

Reject any component that does not fit in the remaining record bytes before using it. In get_symlink_chunk() return NULL, like the existing output-buffer (plimit) checks, so a malformed record makes readlink() fail with -EIO rather than silently returning a truncated target; in parse_rock_ridge_inode_internal() stop the inode-size walk.

Affected Software

Weaknesses

References

• https://git.kernel.org/stable/c/1015e1c4b2fadd9c09704e24738e46598778c869
• https://git.kernel.org/stable/c/36fe7d25dbc40da0c6b1dd4513a4f69ac6164eee
• https://git.kernel.org/stable/c/a22cb6bb54dc167047ea9e70d97dfbc2c15649e3
• https://git.kernel.org/stable/c/b736b12108fd116c41777628f5a333791604df26
• https://git.kernel.org/stable/c/6bf41db09ef935d76fcc84ccf213b42c18de95ee
• https://git.kernel.org/stable/c/b5699642640d6cff357638738c5293985cd5a53d
• https://git.kernel.org/stable/c/9830725078c8483c6831ec10222ae724806ea36b
• https://git.kernel.org/stable/c/5fa1d6a5ec2356d2107dead614437c66fa7138b1

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