CVE-2026-43458

Summary

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

serial: caif: hold tty->link reference in ldisc_open and ser_release

A reproducer triggers a KASAN slab-use-after-free in pty_write_room() when caif_serial's TX path calls tty_write_room(). The faulting access is on tty->link->port.

Hold an extra kref on tty->link for the lifetime of the caif_serial line discipline: get it in ldisc_open() and drop it in ser_release(), and also drop it on the ldisc_open() error path.

With this change applied, the reproducer no longer triggers the UAF in my testing.

Affected Software

VendorProductVersion RangeStatus
LinuxLinuxe31d5a05948e4478ba8396063d1e1f39880928e2 < 23a3ac2e2262a291498567418227b99e1f3606b1affected
LinuxLinuxe31d5a05948e4478ba8396063d1e1f39880928e2 < 52135420e9f75853ea0c6cea7b736e3e98495f7daffected
LinuxLinuxe31d5a05948e4478ba8396063d1e1f39880928e2 < ca2ceba983bb23ea0202c2882d963253416654a3affected
LinuxLinuxe31d5a05948e4478ba8396063d1e1f39880928e2 < 8460187b4852fd00bd1c76394358053f3fa4d089affected
LinuxLinuxe31d5a05948e4478ba8396063d1e1f39880928e2 < 27e43356d0defb9fc7fa25265219a3ffeb7b3e98affected
LinuxLinuxe31d5a05948e4478ba8396063d1e1f39880928e2 < 35b58d3bc716ebb9ebd10fe1cac8c1177242511caffected
LinuxLinuxe31d5a05948e4478ba8396063d1e1f39880928e2 < 97a0bb491cae39478c6225381f14e9ac67b7bba7affected
LinuxLinuxe31d5a05948e4478ba8396063d1e1f39880928e2 < 288598d80a068a0e9281de35bcb4ce495f189e2aaffected
LinuxLinux2.6.35affected
LinuxLinux0 < 2.6.35unaffected
LinuxLinux5.10.253 <= 5.10.*unaffected
LinuxLinux5.15.203 <= 5.15.*unaffected
LinuxLinux6.1.167 <= 6.1.*unaffected
LinuxLinux6.6.130 <= 6.6.*unaffected
LinuxLinux6.12.78 <= 6.12.*unaffected
LinuxLinux6.18.19 <= 6.18.*unaffected
LinuxLinux6.19.9 <= 6.19.*unaffected
LinuxLinux7.0 <= *unaffected

Weaknesses

References