Linux Kernel up to 6.18.32/7.0.6/7.1-rc2 papr-hvpipe papr_hvpipe_dev_create_handle null pointer dereference

Summaryinfo

A vulnerability has been found in Linux Kernel up to 6.18.32/7.0.6/7.1-rc2 and classified as critical. Affected is the function papr_hvpipe_dev_create_handle of the component papr-hvpipe. This manipulation causes null pointer dereference. This vulnerability is tracked as CVE-2026-46118. No exploit exists. The affected component should be upgraded.

Detailsinfo

A vulnerability classified as critical was found in Linux Kernel up to 6.18.32/7.0.6/7.1-rc2. Affected by this vulnerability is the function papr_hvpipe_dev_create_handle of the component papr-hvpipe. The manipulation with an unknown input leads to a null pointer dereference vulnerability. The CWE definition for the vulnerability is CWE-476. A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit. As an impact it is known to affect availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: pseries/papr-hvpipe: Fix null ptr deref in papr_hvpipe_dev_create_handle() commit 6d3789d347a7 ("papr-hvpipe: convert papr_hvpipe_dev_create_handle() to FD_PREPARE()"), changed the create handle to FD_PREPARE(), but it caused kernel null-ptr-deref because after call to retain_and_null_ptr(src_info), src_info is re-used for adding it to the global list. Getting the following kernel panic in papr_hvpipe_dev_create_handle() when trying to add src_info to the list. Kernel attempted to write user page (0) - exploit attempt? (uid: 0) BUG: Kernel NULL pointer dereference on write at 0x00000000 Faulting instruction address: 0xc0000000001b44a0 Oops: Kernel access of bad area, sig: 11 [#1] ... Call Trace: papr_hvpipe_dev_ioctl+0x1f4/0x48c (unreliable) sys_ioctl+0x528/0x1064 system_call_exception+0x128/0x360 system_call_vectored_common+0x15c/0x2ec Now, the error handling with FD_PREPARE's file cleanup and __free(kfree) auto cleanup is getting too convoluted. This is mainly because we need to ensure only 1 user get the srcID handle. To simplify this, we allocate prepare the src_info in the beginning and add it to the global list under a spinlock after checking that no duplicates exist. This simplify the error handling where if the FD_ADD fails, we can simply remove the src_info from the list and consume any pending msg in hvpipe to be cleared, after src_info became visible in the global list.

It is possible to read the advisory at git.kernel.org. This vulnerability is known as CVE-2026-46118 since 05/13/2026. The exploitation appears to be difficult. Technical details of the vulnerability are known, but there is no available exploit.

Upgrading to version 6.18.33, 7.0.7 or 7.1-rc3 eliminates this vulnerability. Applying the patch 735439394dde8462f9b50566727fbe333beaadaf/cf51bec1560f8bf115d1476f60335f9d90e110b0/1b9f7aafa44f5ce852c00509104d10fd9eb0f402 is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 6.18.0
• 6.18.1
• 6.18.2
• 6.18.3
• 6.18.4
• 6.18.5
• 6.18.6
• 6.18.7
• 6.18.8
• 6.18.9
• 6.18.10
• 6.18.11
• 6.18.12
• 6.18.13
• 6.18.14
• 6.18.15
• 6.18.16
• 6.18.17
• 6.18.18
• 6.18.19
• 6.18.20
• 6.18.21
• 6.18.22
• 6.18.23
• 6.18.24
• 6.18.25
• 6.18.26
• 6.18.27
• 6.18.28
• 6.18.29
• 6.18.30
• 6.18.31
• 6.18.32
• 7.0.0
• 7.0.1
• 7.0.2
• 7.0.3
• 7.0.4
• 7.0.5
• 7.0.6
• 7.1-rc1
• 7.1-rc2

License

• open-source

Website

• Vendor: https://www.kernel.org/

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