Bug 2363472 (CVE-2022-49810)
| Summary: | CVE-2022-49810 kernel: netfs: Fix missing xas_retry() calls in xarray iteration | ||
|---|---|---|---|
| Product: | [Other] Security Response | Reporter: | OSIDB Bzimport <bzimport> |
| Component: | vulnerability | Assignee: | Product Security DevOps Team <prodsec-dev> |
| Status: | NEW --- | QA Contact: | |
| Severity: | medium | Docs Contact: | |
| Priority: | medium | ||
| Version: | unspecified | CC: | dfreiber, drow, jburrell, vkumar |
| Target Milestone: | --- | Keywords: | Security |
| Target Release: | --- | ||
| Hardware: | All | ||
| OS: | Linux | ||
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| Fixed In Version: | Doc Type: | --- | |
| Doc Text: | Story Points: | --- | |
| Clone Of: | Environment: | ||
| Last Closed: | Type: | --- | |
| Regression: | --- | Mount Type: | --- |
| Documentation: | --- | CRM: | |
| Verified Versions: | Category: | --- | |
| oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |
| Cloudforms Team: | --- | Target Upstream Version: | |
| Embargoed: | |||
In the Linux kernel, the following vulnerability has been resolved: netfs: Fix missing xas_retry() calls in xarray iteration netfslib has a number of places in which it performs iteration of an xarray whilst being under the RCU read lock. It *should* call xas_retry() as the first thing inside of the loop and do "continue" if it returns true in case the xarray walker passed out a special value indicating that the walk needs to be redone from the root[*]. Fix this by adding the missing retry checks. [*] I wonder if this should be done inside xas_find(), xas_next_node() and suchlike, but I'm told that's not an simple change to effect. This can cause an oops like that below. Note the faulting address - this is an internal value (|0x2) returned from xarray. BUG: kernel NULL pointer dereference, address: 0000000000000402 ... RIP: 0010:netfs_rreq_unlock+0xef/0x380 [netfs] ... Call Trace: netfs_rreq_assess+0xa6/0x240 [netfs] netfs_readpage+0x173/0x3b0 [netfs] ? init_wait_var_entry+0x50/0x50 filemap_read_page+0x33/0xf0 filemap_get_pages+0x2f2/0x3f0 filemap_read+0xaa/0x320 ? do_filp_open+0xb2/0x150 ? rmqueue+0x3be/0xe10 ceph_read_iter+0x1fe/0x680 [ceph] ? new_sync_read+0x115/0x1a0 new_sync_read+0x115/0x1a0 vfs_read+0xf3/0x180 ksys_read+0x5f/0xe0 do_syscall_64+0x38/0x90 entry_SYSCALL_64_after_hwframe+0x44/0xae Changes: ======== ver #2) - Changed an unsigned int to a size_t to reduce the likelihood of an overflow as per Willy's suggestion. - Added an additional patch to fix the maths.