Bug 2312070 (CVE-2024-46682)

Summary: CVE-2024-46682 kernel: nfsd: prevent panic for nfsv4.0 closed files in nfs4_show_open
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Priority: low    
Version: unspecifiedCC: dfreiber, drow, jburrell, vkumar
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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Bug Depends On: 2312186    
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Description OSIDB Bzimport 2024-09-13 06:20:56 UTC
In the Linux kernel, the following vulnerability has been resolved:

nfsd: prevent panic for nfsv4.0 closed files in nfs4_show_open

Prior to commit 3f29cc82a84c ("nfsd: split sc_status out of
sc_type") states_show() relied on sc_type field to be of valid
type before calling into a subfunction to show content of a
particular stateid. From that commit, we split the validity of
the stateid into sc_status and no longer changed sc_type to 0
while unhashing the stateid. This resulted in kernel oopsing
for nfsv4.0 opens that stay around and in nfs4_show_open()
would derefence sc_file which was NULL.

Instead, for closed open stateids forgo displaying information
that relies of having a valid sc_file.

To reproduce: mount the server with 4.0, read and close
a file and then on the server cat /proc/fs/nfsd/clients/2/states

[  513.590804] Call trace:
[  513.590925]  _raw_spin_lock+0xcc/0x160
[  513.591119]  nfs4_show_open+0x78/0x2c0 [nfsd]
[  513.591412]  states_show+0x44c/0x488 [nfsd]
[  513.591681]  seq_read_iter+0x5d8/0x760
[  513.591896]  seq_read+0x188/0x208
[  513.592075]  vfs_read+0x148/0x470
[  513.592241]  ksys_read+0xcc/0x178