CVE-2026-64452

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

6lowpan: fix NHC entry use-after-free on error path

lowpan_nhc_do_uncompression() looks up an NHC descriptor while holding

lowpan_nhc_lock. If the descriptor has no uncompress callback, the error

path drops the lock before printing nhc->name.

lowpan_nhc_del() removes descriptors under the same lock and then relies

on synchronize_net() before the owning module can be unloaded. That only

waits for net RX RCU readers. lowpan_header_decompress() is also exported

and can be reached from callers that are not necessarily covered by the net

core RX critical section, for example the Bluetooth 6LoWPAN L2CAP receive

path.

This leaves a race where one task drops lowpan_nhc_lock in the error path,

another task unregisters and frees the matching descriptor after

synchronize_net() returns, and the first task then dereferences nhc->name

for the warning.

With the post-unlock window widened, KASAN reports:

BUG: KASAN: slab-use-after-free in lowpan_nhc_do_uncompression+0x1f4/0x220

Read of size 8

lowpan_nhc_do_uncompression

lowpan_header_decompress

Fix this by printing the warning before dropping lowpan_nhc_lock, so the

descriptor name is read while unregister is still excluded. The malformed

packet is still rejected with -ENOTSUPP.