Bug 2347793 (CVE-2022-49393)

Summary: CVE-2022-49393 kernel: misc: fastrpc: fix list iterator in fastrpc_req_mem_unmap_impl
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
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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 03:06:57 UTC
In the Linux kernel, the following vulnerability has been resolved:

misc: fastrpc: fix list iterator in fastrpc_req_mem_unmap_impl

This is another instance of incorrect use of list iterator and
checking it for NULL.

The list iterator value 'map' will *always* be set and non-NULL
by list_for_each_entry(), so it is incorrect to assume that the
iterator value will be NULL if the list is empty (in this case, the
check 'if (!map) {' will always be false and never exit as expected).

To fix the bug, use a new variable 'iter' as the list iterator,
while use the original variable 'map' as a dedicated pointer to
point to the found element.

Without this patch, Kernel crashes with below trace:

Unable to handle kernel access to user memory outside uaccess routines
 at virtual address 0000ffff7fb03750
...
Call trace:
 fastrpc_map_create+0x70/0x290 [fastrpc]
 fastrpc_req_mem_map+0xf0/0x2dc [fastrpc]
 fastrpc_device_ioctl+0x138/0xc60 [fastrpc]
 __arm64_sys_ioctl+0xa8/0xec
 invoke_syscall+0x48/0x114
 el0_svc_common.constprop.0+0xd4/0xfc
 do_el0_svc+0x28/0x90
 el0_svc+0x3c/0x130
 el0t_64_sync_handler+0xa4/0x130
 el0t_64_sync+0x18c/0x190
Code: 14000016 f94000a5 eb05029f 54000260 (b94018a6)
---[ end trace 0000000000000000 ]---

Comment 1 Avinash Hanwate 2025-02-26 19:59:50 UTC
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025022649-CVE-2022-49393-dd81@gregkh/T