CVE-2021-47321

watchdog: Fix possible use-after-free by calling del_timer_sync()

HIGH
7.8
CVSS Score
Published: May 21, 2024 at 02:35 PM UTC
Updated: June 17, 2026 at 04:17 AM UTC
1 product affected across 1 vendorLinux Kernel

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Severity
HIGH7.8
Exploit prediction
EPSS 0.2%
SSVC
No known exploit

Description

In the Linux kernel, the following vulnerability has been resolved: watchdog: Fix possible use-after-free by calling del_timer_sync() This driver's remove path calls del_timer(). However, that function does not wait until the timer handler finishes. This means that the timer handler may still be running after the driver's remove function has finished, which would result in a use-after-free. Fix by calling del_timer_sync(), which makes sure the timer handler has finished, and unable to re-schedule itself.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 4.4.2764.10 ≤ v < 4.14.2404.15 ≤ v < 4.19.1984.20 ≤ v < 5.4.1344.3 ≤ v < 4.14.2404.3 ≤ v < 4.19.1984.3 ≤ v < 4.4.2764.3 ≤ v < 4.9.2764.3 ≤ v < 5.10.524.3 ≤ v < 5.12.194.3 ≤ v < 5.13.44.3 ≤ v < 5.144.3 ≤ v < 5.4.1344.5 ≤ v < 4.9.2765.11 ≤ v < 5.12.95.13 ≤ v < 5.13.45.5 ≤ v < 5.10.524.37c25f8c9f67708e6464d2221bc311cbd99e950dc
Vendor states this is fixed in 1a053c4d716898a53c2e31c574a70ea0c37044a3 (fixed)
Vendor states this is fixed in 4c05dac488a660fe2925c047ecb119e7afaaeb1e (fixed)
Vendor states this is fixed in 58606882ad8ec6c39e0f40344b922921ef94ab4d (fixed)
Vendor states this is fixed in 66ba9cf929b1c4fabf545bd4c18f6f64e23e46e4 (fixed)
Vendor states this is fixed in 8bec568d7518b1504a602ed5376bb322e4dbb270 (fixed)
Vendor states this is fixed in ca96b8ea5e74956071154bdb456778cc3027e79f (fixed)
Vendor states this is fixed in d0212f095ab56672f6f36aabc605bda205e1e0bf (fixed)
Vendor states this is fixed in db222f1477ad5692cd454709b714949807e5d111 (fixed)
Vendor states this is fixed in ecd620e0fb1ff7f78fdb593379b2e6938c99707a (fixed)
Vendor states this is fixed in 4.14.240 (unaffected)
Vendor states this is fixed in 4.19.198 (unaffected)
Vendor states this is fixed in 4.3 (unaffected)
Vendor states this is fixed in 4.4.276 (unaffected)
Vendor states this is fixed in 4.9.276 (unaffected)
Vendor states this is fixed in 5.10.52 (unaffected)
Vendor states this is fixed in 5.12.19 (unaffected)
Affected range stops below 5.12.9, so it looks safe — our inference, not a vendor statement
Vendor states this is fixed in 5.13.4 (unaffected)
Vendor states this is fixed in 5.14 (unaffected)
Vendor states this is fixed in 5.4.134 (unaffected)

References (9)

Patch
Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
https://git.kernel.org/stable/c/1a053c4d716898a53c2e31c574a70ea0c37044a3
Patch
Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
https://git.kernel.org/stable/c/4c05dac488a660fe2925c047ecb119e7afaaeb1e
Patch
Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
https://git.kernel.org/stable/c/58606882ad8ec6c39e0f40344b922921ef94ab4d
Patch
Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
https://git.kernel.org/stable/c/66ba9cf929b1c4fabf545bd4c18f6f64e23e46e4
Patch
Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
https://git.kernel.org/stable/c/8bec568d7518b1504a602ed5376bb322e4dbb270
Patch
Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
https://git.kernel.org/stable/c/ca96b8ea5e74956071154bdb456778cc3027e79f
Patch
Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
https://git.kernel.org/stable/c/d0212f095ab56672f6f36aabc605bda205e1e0bf
Patch
Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
https://git.kernel.org/stable/c/db222f1477ad5692cd454709b714949807e5d111

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

Attack Vector
LOCAL
Complexity
LOW
Privileges
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
HIGH
Vector?

Quick Info

StatusANALYZED
CWE
CWE-416

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