CVE-2024-36939 — nfs: Handle error of rpc_proc_register() in nfs_net_init().

Affected: Linux, Siemens SIMATIC S7-1500 TM MFP - GNU/Linux subsystem

In the Linux kernel, the following vulnerability has been resolved:

nfs: Handle error of rpc_proc_register() in nfs_net_init().

syzkaller reported a warning [0] triggered while destroying immature netns.

rpc_proc_register() was called in init_nfs_fs(), but its error has been ignored since at least the initial commit 1da177e4c3f4 ("Linux-2.6.12-rc2").

Recently, commit d47151b79e32 ("nfs: expose /proc/net/sunrpc/nfs in net namespaces") converted the procfs to per-netns and made the problem more visible.

Even when rpc_proc_register() fails, nfs_net_init() could succeed, and thus nfs_net_exit() will be called while destroying the netns.

Then, remove_proc_entry() will be called for non-existing proc directory and trigger the warning below.

Let's handle the error of rpc_proc_register() properly in nfs_net_init().

[0]: name 'nfs' WARNING: CPU: 1 PID: 1710 at fs/proc/generic.c:711 remove_proc_entry+0x1bb/0x2d0 fs/proc/generic.c:711 Modules linked in: CPU: 1 PID: 1710 Comm: syz-executor.2 Not tainted 6.8.0-12822-gcd51db110a7e #12 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014 RIP: 0010:remove_proc_entry+0x1bb/0x2d0 fs/proc/generic.c:711 Code: 41 5d 41 5e c3 e8 85 09 b5 ff 48 c7 c7 88 58 64 86 e8 09 0e 71 02 e8 74 09 b5 ff 4c 89 e6 48 c7 c7 de 1b 80 84 e8 c5 ad 97 ff <0f> 0b eb b1 e8 5c 09 b5 ff 48 c7 c7 88 58 64 86 e8 e0 0d 71 02 eb RSP: 0018:ffffc9000c6d7ce0 EFLAGS: 00010286 RAX: 0000000000000000 RBX: ffff8…

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CVE-2024-36939 — nfs: Handle error of rpc_proc_register() in nfs_net_init().