bpf, sockmap: Fix skb refcnt race after locking changes
In the Linux kernel, the following vulnerability has been resolved: bpf, sockmap: Fix skb refcnt race after locking changes There is a race where skb's from the sk_psock_backlog can be referenced after userspace side has already skb_consumed() the sk_buff and its refcnt dropped to zer0 causing use after free. The flow is the following: while ((skb = skb_peek(&psock->ingress_skb)) sk_psock_handle_Skb(psock, skb, ..., ingress) if (!ingress) ... sk_psock_skb_ingress sk_psock_skb_ingress_enqueue(skb) msg->skb = skb sk_psock_queue_msg(psock, msg) skb_dequeue(&psock->ingress_skb) The sk_psock_queue_msg() puts the msg on the ingress_msg queue. This is what the application reads when recvmsg() is called. An application can read this anytime after the msg is placed on the queue. The recvmsg hook will also read msg->skb and then after user space reads the msg will call consume_skb(skb) on it effectively free'ing it. But, the race is in above where backlog queue still has a reference to the skb and calls skb_dequeue(). If the skb_dequeue happens after the user reads and free's the skb we have a use after free. The !ingress case does not suffer from this problem because it uses sendmsg_*(sk, msg) which does not pass the sk_buff further down the stack. The following splat was observed with 'test_progs -t sockmap_listen': [ 1022.710250][ T2556] general protection fault, ... [...] [ 1022.712830][ T2556] Workqueue: events sk_psock_backlog [ 1022.713262][ T2556] RIP: 0010:skb_dequeue+0x4c/0x8
CVE-2023-53836
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: cve:CVE-2023-53836
Linux
Source reference: /containers/cna/affected/0/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Linux
Source reference: /containers/cna/affected/1/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "799aa7f98d53e0f541fa6b4dc9aa47b4ff2178e3",
"lessThan": "65ad600b9bde68d2d28709943ab00b51ca8f0a1d",
"versionType": "git"
},
{
"status": "affected",
"version": "799aa7f98d53e0f541fa6b4dc9aa47b4ff2178e3",
"lessThan": "923877254f002ae87d441382bb1096d9e773d56d",
"versionType": "git"
},
{
"status": "affected",
"version": "799aa7f98d53e0f541fa6b4dc9aa47b4ff2178e3",
"lessThan": "e6b5e47adb9166e732cdf7e6e034946e3f89f36d",
"versionType": "git"
},
{
"status": "affected",
"version": "799aa7f98d53e0f541fa6b4dc9aa47b4ff2178e3",
"lessThan": "a454d84ee20baf7bd7be90721b9821f73c7d23d9",
"versionType": "git"
}
],
"programFiles": [
"net/core/skmsg.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "5.13"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "5.13",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "5.15.189",
"versionType": "semver",
"lessThanOrEqual": "5.15.*"
},
{
"status": "unaffected",
"version": "6.1.54",
"versionType": "semver",
"lessThanOrEqual": "6.1.*"
},
{
"status": "unaffected",
"version": "6.5.4",
"versionType": "semver",
"lessThanOrEqual": "6.5.*"
},
{
"status": "unaffected",
"version": "6.6",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"net/core/skmsg.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2023-53836
Source reference:
/cveMetadata/cveId
Publisher severity
high
Source reference: /containers/cna/metrics
- Event
- #30329 · Revision 1
- Added to Heist Feed
- Publisher date