Description (CNA)
In the Linux kernel, the following vulnerability has been resolved: auxdisplay: line-display: fix OOB read on zero-length message_store() linedisp_display() unconditionally reads msg[count - 1] before checking whether count is zero, so a write of zero bytes to the message sysfs attribute hits msg[-1]: write(fd, "", 0); -> message_store(..., buf, count=0) -> linedisp_display(linedisp, buf, count=0) -> msg[count - 1] == '\n' ; OOB read The kernfs write buffer for that store is a 1-byte allocation (kernfs_fop_write_iter() does kmalloc(len + 1) with len == 0), so msg[-1] is a 1-byte read before the slab object. On a KASAN-enabled kernel this trips an out-of-bounds report and panics; on stock kernels it silently reads adjacent slab data and, if that byte happens to be '\n', the following count-- wraps ssize_t 0 to -1 and is then passed to kmemdup_nul(). linedisp_display() is reached from the message_store() sysfs callback (drivers/auxdisplay/line-display.c message attribute, mode 0644) and from the in-tree initial-message setup with count == -1, so the OOB path is only userspace-triggerable via zero-byte writes; vfs_write() does not short-circuit on count == 0 and kernfs_fop_write_iter() dispatches the store callback regardless. Guard the trailing-newline trim with a count check. The existing if (!count) block then takes the clear-display path unchanged. Affects every auxdisplay driver that registers via linedisp_register() / linedisp_attach(): ht16k33, max6959, img-ascii-lcd, seg-led-gpio.
Affected (CNA)
| Vendor / product | Versions |
|---|---|
| Linux / Linux | affected 7e76aece6f036cb7ada4858d6aa73825bfe22983 before ca5b0781946d5083ceafa752141f47f085853620; affected 7e76aece6f036cb7ada4858d6aa73825bfe22983 before 8776032fe989a9b5fc77f2de5e03e4adb44c630e; affected 7e76aece6f036cb7ada4858d6aa73825bfe22983 before 3859960daeb9b7b39b9847b5b0113bc6081eb735; affected 7e76aece6f036cb7ada4858d6aa73825bfe22983 before 197476b126010bac1b3199833c6966cd6f54c2a9; affected 7e76aece6f036cb7ada4858d6aa73825bfe22983 before 6ad4f75ef9f3372fce8cad494e789ac6a5507bef; affected 7e76aece6f036cb7ada4858d6aa73825bfe22983 before a7511dcd9dd4bc55d123f9b800c8a4ed2662e5c6 |
| Linux / Linux | affected 5.16; unaffected 0 before 5.16; unaffected 6.1.176 through 6.1.*; unaffected 6.6.143 through 6.6.*; unaffected 6.12.93 through 6.12.*; unaffected 6.18.35 through 6.18.*; unaffected 7.0.12 through 7.0.*; unaffected 7.1 through * |
CWE
No CWE identifiers supplied.
References
- https://git.kernel.org/stable/c/ca5b0781946d5083ceafa752141f47f085853620
- https://git.kernel.org/stable/c/8776032fe989a9b5fc77f2de5e03e4adb44c630e
- https://git.kernel.org/stable/c/3859960daeb9b7b39b9847b5b0113bc6081eb735
- https://git.kernel.org/stable/c/197476b126010bac1b3199833c6966cd6f54c2a9
- https://git.kernel.org/stable/c/6ad4f75ef9f3372fce8cad494e789ac6a5507bef
- https://git.kernel.org/stable/c/a7511dcd9dd4bc55d123f9b800c8a4ed2662e5c6