Bug 2347920 (CVE-2021-47631)

Summary: CVE-2021-47631 kernel: ARM: davinci: da850-evm: Avoid NULL pointer dereference
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Priority: medium    
Version: unspecifiedCC: dfreiber, drow, jburrell, vkumar
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Hardware: All   
OS: Linux   
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Description OSIDB Bzimport 2025-02-26 03:11:22 UTC 
In the Linux kernel, the following vulnerability has been resolved:

ARM: davinci: da850-evm: Avoid NULL pointer dereference

With newer versions of GCC, there is a panic in da850_evm_config_emac()
when booting multi_v5_defconfig in QEMU under the palmetto-bmc machine:

Unable to handle kernel NULL pointer dereference at virtual address 00000020
pgd = (ptrval)
[00000020] *pgd=00000000
Internal error: Oops: 5 [#1] PREEMPT ARM
Modules linked in:
CPU: 0 PID: 1 Comm: swapper Not tainted 5.15.0 #1
Hardware name: Generic DT based system
PC is at da850_evm_config_emac+0x1c/0x120
LR is at do_one_initcall+0x50/0x1e0

The emac_pdata pointer in soc_info is NULL because davinci_soc_info only
gets populated on davinci machines but da850_evm_config_emac() is called
on all machines via device_initcall().

Move the rmii_en assignment below the machine check so that it is only
dereferenced when running on a supported SoC.
Comment 1 Avinash Hanwate 2025-02-26 11:50:47 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025022643-CVE-2021-47631-bcc8@gregkh/T
Comment 2 Avinash Hanwate 2025-02-27 23:57:58 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025022643-CVE-2021-47631-bcc8@gregkh/T