Linux Kernel up to 5.15.45/5.17.13/5.18.2 enter_rtas recursion

Summaryinfo

A vulnerability categorized as critical has been discovered in Linux Kernel up to 5.15.45/5.17.13/5.18.2. This affects the function enter_rtas. Executing a manipulation can lead to recursion. This vulnerability is handled as CVE-2022-49440. There is not any exploit available. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability classified as critical was found in Linux Kernel up to 5.15.45/5.17.13/5.18.2. This vulnerability affects the function enter_rtas. The manipulation with an unknown input leads to a recursion vulnerability. The CWE definition for the vulnerability is CWE-674. The product does not properly control the amount of recursion that takes place, consuming excessive resources, such as allocated memory or the program stack. As an impact it is known to affect availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: powerpc/rtas: Keep MSR[RI] set when calling RTAS RTAS runs in real mode (MSR[DR] and MSR[IR] unset) and in 32-bit big endian mode (MSR[SF,LE] unset). The change in MSR is done in enter_rtas() in a relatively complex way, since the MSR value could be hardcoded. Furthermore, a panic has been reported when hitting the watchdog interrupt while running in RTAS, this leads to the following stack trace: watchdog: CPU 24 Hard LOCKUP watchdog: CPU 24 TB:997512652051031, last heartbeat TB:997504470175378 (15980ms ago) ... Supported: No, Unreleased kernel CPU: 24 PID: 87504 Comm: drmgr Kdump: loaded Tainted: G E X 5.14.21-150400.71.1.bz196362_2-default #1 SLE15-SP4 (unreleased) 0d821077ef4faa8dfaf370efb5fdca1fa35f4e2c NIP: 000000001fb41050 LR: 000000001fb4104c CTR: 0000000000000000 REGS: c00000000fc33d60 TRAP: 0100 Tainted: G E X (5.14.21-150400.71.1.bz196362_2-default) MSR: 8000000002981000 CR: 48800002 XER: 20040020 CFAR: 000000000000011c IRQMASK: 1 GPR00: 0000000000000003 ffffffffffffffff 0000000000000001 00000000000050dc GPR04: 000000001ffb6100 0000000000000020 0000000000000001 000000001fb09010 GPR08: 0000000020000000 0000000000000000 0000000000000000 0000000000000000 GPR12: 80040000072a40a8 c00000000ff8b680 0000000000000007 0000000000000034 GPR16: 000000001fbf6e94 000000001fbf6d84 000000001fbd1db0 000000001fb3f008 GPR20: 000000001fb41018 ffffffffffffffff 000000000000017f fffffffffffff68f GPR24: 000000001fb18fe8 000000001fb3e000 000000001fb1adc0 000000001fb1cf40 GPR28: 000000001fb26000 000000001fb460f0 000000001fb17f18 000000001fb17000 NIP [000000001fb41050] 0x1fb41050 LR [000000001fb4104c] 0x1fb4104c Call Trace: Instruction dump: XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX Oops: Unrecoverable System Reset, sig: 6 [#1] LE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=2048 NUMA pSeries ... Supported: No, Unreleased kernel CPU: 24 PID: 87504 Comm: drmgr Kdump: loaded Tainted: G E X 5.14.21-150400.71.1.bz196362_2-default #1 SLE15-SP4 (unreleased) 0d821077ef4faa8dfaf370efb5fdca1fa35f4e2c NIP: 000000001fb41050 LR: 000000001fb4104c CTR: 0000000000000000 REGS: c00000000fc33d60 TRAP: 0100 Tainted: G E X (5.14.21-150400.71.1.bz196362_2-default) MSR: 8000000002981000 CR: 48800002 XER: 20040020 CFAR: 000000000000011c IRQMASK: 1 GPR00: 0000000000000003 ffffffffffffffff 0000000000000001 00000000000050dc GPR04: 000000001ffb6100 0000000000000020 0000000000000001 000000001fb09010 GPR08: 0000000020000000 0000000000000000 0000000000000000 0000000000000000 GPR12: 80040000072a40a8 c00000000ff8b680 0000000000000007 0000000000000034 GPR16: 000000001fbf6e94 000000001fbf6d84 000000001fbd1db0 000000001fb3f008 GPR20: 000000001fb41018 ffffffffffffffff 000000000000017f fffffffffffff68f GPR24: 000000001fb18fe8 000000001fb3e000 000000001fb1adc0 000000001fb1cf40 GPR28: 000000001fb26000 000000001fb460f0 000000001fb17f18 000000001fb17000 NIP [000000001fb41050] 0x1fb41050 LR [000000001fb4104c] 0x1fb4104c Call Trace: Instruction dump: XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX ---[ end trace 3ddec07f638c34a2 ]--- This happens because MSR[RI] is unset when entering RTAS but there is no valid reason to not set it here. RTAS is expected to be called with MSR[RI] as specified in PAPR+ section "7.2.1 Machine State": R1–7.2.1–9. If called with MSR[RI] equal to 1, then RTAS must protect its own critical regions from recursion by setting the MSR[RI] bit to 0 when in the critical regions. Fixing this by reviewing the way MSR is compute before calling RTAS. Now a hardcoded value meaning real ---truncated---

The advisory is available at git.kernel.org. This vulnerability was named CVE-2022-49440 since 02/26/2025. The exploitation appears to be difficult. Technical details are known, but there is no available exploit.

Upgrading to version 5.15.46, 5.17.14 or 5.18.3 eliminates this vulnerability. Applying the patch 5ca40fcf0da0ce2b5bc44e7d8b036535955f2e3d/5f4367448f6817c8a0e94dc9736ed84fa8eee4a3/c9c41f0273826a13ac93124e66a4ff45df281ba0/b6b1c3ce06ca438eb24e0f45bf0e63ecad0369f5 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

• 5.15.0
• 5.15.1
• 5.15.2
• 5.15.3
• 5.15.4
• 5.15.5
• 5.15.6
• 5.15.7
• 5.15.8
• 5.15.9
• 5.15.10
• 5.15.11
• 5.15.12
• 5.15.13
• 5.15.14
• 5.15.15
• 5.15.16
• 5.15.17
• 5.15.18
• 5.15.19
• 5.15.20
• 5.15.21
• 5.15.22
• 5.15.23
• 5.15.24
• 5.15.25
• 5.15.26
• 5.15.27
• 5.15.28
• 5.15.29
• 5.15.30
• 5.15.31
• 5.15.32
• 5.15.33
• 5.15.34
• 5.15.35
• 5.15.36
• 5.15.37
• 5.15.38
• 5.15.39
• 5.15.40
• 5.15.41
• 5.15.42
• 5.15.43
• 5.15.44
• 5.15.45
• 5.17.0
• 5.17.1
• 5.17.2
• 5.17.3
• 5.17.4
• 5.17.5
• 5.17.6
• 5.17.7
• 5.17.8
• 5.17.9
• 5.17.10
• 5.17.11
• 5.17.12
• 5.17.13
• 5.18.0
• 5.18.1
• 5.18.2

License

• open-source

Website

• Vendor: https://www.kernel.org/

CPE 2.3info

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CPE 2.2info

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