Description (CNA)
In the Linux kernel, the following vulnerability has been resolved: serial: core: fix infinite loop in handle_tx() for PORT_UNKNOWN uart_write_room() and uart_write() behave inconsistently when xmit_buf is NULL (which happens for PORT_UNKNOWN ports that were never properly initialized): - uart_write_room() returns kfifo_avail() which can be > 0 - uart_write() checks xmit_buf and returns 0 if NULL This inconsistency causes an infinite loop in drivers that rely on tty_write_room() to determine if they can write: while (tty_write_room(tty) > 0) { written = tty->ops->write(...); // written is always 0, loop never exits } For example, caif_serial's handle_tx() enters an infinite loop when used with PORT_UNKNOWN serial ports, causing system hangs. Fix by making uart_write_room() also check xmit_buf and return 0 if it's NULL, consistent with uart_write(). Reproducer: https://gist.github.com/mrpre/d9a694cc0e19828ee3bc3b37983fde13
Affected (CNA)
| Vendor / product | Versions |
|---|---|
| Linux / Linux | affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before c9e845014723d552944cec4e146ec7b841cda34d; affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before d45cfa70bf0159afb31cb03d2d16ec5a5053460c; affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before efe85a557186b7fe915572ae93a8f3f78bfd9a22; affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before bc70f2b36cf474d5cc8ecbcaf57f3e326fdec67c; affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before 455ce986fa356ff43a43c0d363ba95fa152f21d5 |
| Linux / Linux | affected 2.6.12; unaffected 0 before 2.6.12; unaffected 6.6.160 through 6.6.*; unaffected 6.12.114 through 6.12.*; unaffected 6.18.20 through 6.18.*; unaffected 6.19.10 through 6.19.*; unaffected 7.0 through * |
CWE
No CWE identifiers supplied.
References
- https://git.kernel.org/stable/c/c9e845014723d552944cec4e146ec7b841cda34d
- https://git.kernel.org/stable/c/d45cfa70bf0159afb31cb03d2d16ec5a5053460c
- https://git.kernel.org/stable/c/efe85a557186b7fe915572ae93a8f3f78bfd9a22
- https://git.kernel.org/stable/c/bc70f2b36cf474d5cc8ecbcaf57f3e326fdec67c
- https://git.kernel.org/stable/c/455ce986fa356ff43a43c0d363ba95fa152f21d5