Bug 2493768 (CVE-2026-53304) - CVE-2026-53304 kernel: scsi: sg: Resolve soft lockup issue when opening /dev/sgX
Summary: CVE-2026-53304 kernel: scsi: sg: Resolve soft lockup issue when opening /dev/sgX
Keywords:
Status: NEW
Alias: CVE-2026-53304
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
low
low
Target Milestone: ---
Assignee: Product Security
QA Contact:
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2026-06-26 21:06 UTC by OSIDB Bzimport
Modified: 2026-06-29 08:18 UTC (History)
2 users (show)

Fixed In Version:
Clone Of:
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Description OSIDB Bzimport 2026-06-26 21:06:22 UTC
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.

Comment 1 Mauro Matteo Cascella 2026-06-29 08:17:04 UTC
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026062619-CVE-2026-53304-9e19@gregkh/T


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