Bug 2457276 (CVE-2026-31412) - CVE-2026-31412 kernel: usb: gadget: f_mass_storage: Fix potential integer overflow in check_command_size_in_blocks()
Summary: CVE-2026-31412 kernel: usb: gadget: f_mass_storage: Fix potential integer ove...
Keywords:
Status: NEW
Alias: CVE-2026-31412
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
unspecified
unspecified
Target Milestone: ---
Assignee: Product Security DevOps Team
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Blocks:
TreeView+ depends on / blocked
 
Reported: 2026-04-10 11:01 UTC by OSIDB Bzimport
Modified: 2026-04-10 14:44 UTC (History)
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Description OSIDB Bzimport 2026-04-10 11:01:27 UTC
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.


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