CVE-2024-26870: NFSv4.2: fix nfs4_listxattr kernel BUG at mm/usercopy.c:102
In the Linux kernel, the following vulnerability has been resolved:
NFSv4.2: fix nfs4listxattr kernel BUG at mm/usercopy.c:102
A call to listxattr() with a buffer size = 0 returns the actual size of the buffer needed for a subsequent call. When size > 0, nfs4listxattr() does not return an error because either genericlistxattr() or nfs4listxattrnfs4label() consumes exactly all the bytes then size is 0 when calling nfs4listxattrnfs4user() which then triggers the following kernel BUG:
[ 99.403778] kernel BUG at mm/usercopy.c:102! [ 99.404063] Internal error: Oops - BUG: 00000000f2000800 [#1] SMP [ 99.408463] CPU: 0 PID: 3310 Comm: python3 Not tainted 6.6.0-61.fc40.aarch64 #1 [ 99.415827] Call trace: [ 99.415985] usercopyabort+0x70/0xa0 [ 99.416227] checkheapobject+0x134/0x158 [ 99.416505] checkheapobject+0x150/0x188 [ 99.416696] checkobjectsize.part.0+0x78/0x168 [ 99.416886] checkobjectsize+0x28/0x40 [ 99.417078] listxattr+0x8c/0x120 [ 99.417252] pathlistxattr+0x78/0xe0 [ 99.417476] arm64syslistxattr+0x28/0x40 [ 99.417723] invokesyscall+0x78/0x100 [ 99.417929] el0svccommon.constprop.0+0x48/0xf0 [ 99.418186] doel0svc+0x24/0x38 [ 99.418376] el0svc+0x3c/0x110 [ 99.418554] el0t64synchandler+0x120/0x130 [ 99.418788] el0t64sync+0x194/0x198 [ 99.418994] Code: aa0003e3 d000a3e0 91310000 97f49bdb (d4210000)
Issue is reproduced when genericlistxattr() returns 'system.nfs4acl', thus calling lisxattr() with size = 16 will trigger the bug.
Add check on nfs4listxattr() to return ERANGE error when it is called with size > 0 and the return value is greater than size.
Other sources
In the Linux kernel, the following vulnerability has been resolved:
NFSv4.2: fix nfs4listxattr kernel BUG at mm/usercopy.c:102
The Linux kernel CVE team has assigned CVE-2024-26870 to this issue.
Upstream advisory: https://lore.kernel.org/linux-cve-announce/2024041738-CVE-2024-26870-7aea@gregkh/T
— Red Hat
Linux Kernel is vulnerable to a denial of service, caused by a nfs4listxattr kernel BUG at mm/usercopy.c. By sending a specially crafted request, a local authenticated attacker could exploit this vulnerability to cause a denial of service condition.
— IBM
Affected Software
Remediation
Event History
Frequently Asked Questions
What is the severity of CVE-2024-26870?
CVE-2024-26870 has been classified with a significant severity due to the potential for a kernel BUG in NFSv4.2.
How do I fix CVE-2024-26870?
To remediate CVE-2024-26870, upgrade your Linux kernel to the latest available versions as specified: 5.10.214, 5.15.153, 6.1.83, 6.6.23, 6.7.11, 6.8.2, or 6.9.
Which Linux kernel versions are affected by CVE-2024-26870?
CVE-2024-26870 affects various kernel versions including those below 5.10.214, 5.15.153, 6.1.83, 6.6.23, 6.7.11, 6.8.2, and 6.9.
Is there a specific command to check the current kernel version for CVE-2024-26870?
You can check your current kernel version by running the command 'uname -r' in the terminal.
What are the implications of not addressing CVE-2024-26870?
Failure to address CVE-2024-26870 may lead to system instability and potential exploitation through the NFSv4.2 interface.