Bug 2486454 (CVE-2026-46294) - CVE-2026-46294 kernel: dm: fix a buffer overflow in ioctl processing
Summary: CVE-2026-46294 kernel: dm: fix a buffer overflow in ioctl processing
Keywords:
Status: NEW
Alias: CVE-2026-46294
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Product Security
QA Contact:
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2026-06-08 17:02 UTC by OSIDB Bzimport
Modified: 2026-06-08 19:18 UTC (History)
2 users (show)

Fixed In Version:
Clone Of:
Environment:
Last Closed:
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Description OSIDB Bzimport 2026-06-08 17:02:47 UTC
In the Linux kernel, the following vulnerability has been resolved:

dm: fix a buffer overflow in ioctl processing

Tony Asleson (using Claude) found a buffer overflow in dm-ioctl in the
function retrieve_status:

1. The code in retrieve_status checks that the output string fits into
   the output buffer and writes the output string there
2. Then, the code aligns the "outptr" variable to the next 8-byte
   boundary:
	outptr = align_ptr(outptr);
3. The alignment doesn't check overflow, so outptr could point past the
   buffer end
4. The "for" loop is iterated again, it executes:
	remaining = len - (outptr - outbuf);
5. If "outptr" points past "outbuf + len", the arithmetics wraps around
   and the variable "remaining" contains unusually high number
6. With "remaining" being high, the code writes more data past the end of
   the buffer

Luckily, this bug has no security implications because:
1. Only root can issue device mapper ioctls
2. The commonly used libraries that communicate with device mapper
   (libdevmapper and devicemapper-rs) use buffer size that is aligned to
   8 bytes - thus, "outptr = align_ptr(outptr)" can't overshoot the input
   buffer and the bug can't happen accidentally


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