A recent vulnerability found in the Linux kernel relating to the media: dvb-frontends function has been resolved. This particular issue dealt with a stack frame size error that occurred with the clang programming language within the stv0367ter_set_frontend function. Specifically, the error message reported:

drivers/media/dvb-frontends/stv0367.c:1222:12: error: stack frame size (3624) exceeds limit (2048) in 'stv0367ter_set_frontend' [-Werror,-Wframe-larger-than]
 1214 | static int stv0367ter_set_frontend(struct dvb_frontend *fe)

Previous patches had worked around this issue in the stv0367 function by addressing a KASAN (Kernel Address Sanitizer) problem. However, the same problem resurfaced when utilizing the clang programming language. As a result, new measures were taken to fix this vulnerability.

The solution involved reworking the stv0367_writereg() function into a simpler form and additionally marking both register access functions as noinline_for_stack. This modification ensures that the temporary i2c_msg structures will not be duplicated on the stack when KASAN_STACK is enabled.

The following code snippet showcases the changed stv0367_writereg() function

// original stv0367_writereg() function
// ...

// modified stv0367_writereg() function
// ...
// mark as noinline_for_stack so the i2c_msg structures do not get duplicated on the stack
__attribute__((noinline_for_stack))
// ...

For further information on the original vulnerability and the implemented fix, please refer to the following references:

- Linux Kernel Git Repository: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/
- Media: DVB-Frontends Source Code: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/media/dvb-frontends/stv0367.c

Exploit Details

The original stack overflow vulnerability found in the Linux kernel's media: dvb-frontends function could potentially have allowed attackers to execute arbitrary code on affected systems. However, with the new fix implemented, the risk of a successful stack overflow exploit occurring is significantly reduced. By restructuring the stv0367_writereg() function and implementing the noinline_for_stack attribute, the temporary i2c_msg structures are prevented from being duplicated on the stack, thus addressing the issue.

With this vulnerability now resolved, Linux kernel users can feel more secure in knowing that this potential security risk has been addressed. It is always crucial for users and developers to stay up to date with the latest security patches and updates to ensure the safety of their systems.

Timeline

Published on: 05/01/2024 13:15:51 UTC
Last modified on: 06/27/2024 12:15:24 UTC