CVE-2026-31412

Summary

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

usb: gadget: f_mass_storage: Fix potential integer overflow in check_command_size_in_blocks()

The check_command_size_in_blocks() function calculates the data size in bytes by left shifting common->data_size_from_cmnd by the block size (common->curlun->blkbits). However, it does not validate whether this shift operation will cause an integer overflow.

Initially, the block size is set up in fsg_lun_open() , and the common->data_size_from_cmnd is set up in do_scsi_command(). During initialization, there is no integer overflow check for the interaction between two variables.

So if a malicious USB host sends a SCSI READ or WRITE command requesting a large amount of data (common->data_size_from_cmnd), the left shift operation can wrap around. This results in a truncated data size, which can bypass boundary checks and potentially lead to memory corruption or out-of-bounds accesses.

Fix this by using the check_shl_overflow() macro to safely perform the shift and catch any overflows.

Affected Software

Weaknesses

References

• https://git.kernel.org/stable/c/91817ad5452defe69bc7bc0e355f0ed5d01125cc
• https://git.kernel.org/stable/c/ce0caaed5940162780c5c223b8ae54968a5f059b
• https://git.kernel.org/stable/c/228b37936376143f4b60cc6828663f6eaceb81b5
• https://git.kernel.org/stable/c/3428dc5520c811e66622b2f5fa43341bf9a1f8b3
• https://git.kernel.org/stable/c/387ebb0453b99d71491419a5dc4ab4bee0cacbac
• https://git.kernel.org/stable/c/8479891d1f04a8ce55366fe4ca361ccdb96f02e1

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