AI Score
Confidence
Low
EPSS
Percentile
13.0%
SSVC
Exploitation
none
Automatable
no
Technical Impact
partial
In the Linux kernel, the following vulnerability has been resolved:
binder: fix race between mmput() and do_exit()
Task A calls binder_update_page_range() to allocate and insert pages on
a remote address space from Task B. For this, Task A pins the remote mm
via mmget_not_zero() first. This can race with Task B do_exit() and the
final mmput() refcount decrement will come from Task A.
Task A | Task B
------------------±-----------------
mmget_not_zero() |
| do_exit()
| exit_mm()
| mmput()
mmput() |
exit_mmap() |
remove_vma() |
fput() |
In this case, the work of ____fput() from Task B is queued up in Task A
as TWA_RESUME. So in theory, Task A returns to userspace and the cleanup
work gets executed. However, Task A instead sleep, waiting for a reply
from Task B that never comes (it’s dead).
This means the binder_deferred_release() is blocked until an unrelated
binder event forces Task A to go back to userspace. All the associated
death notifications will also be delayed until then.
In order to fix this use mmput_async() that will schedule the work in
the corresponding mm->async_put_work WQ instead of Task A.
[
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "457b9a6f09f0",
"lessThan": "95b1d336b064",
"versionType": "git"
},
{
"status": "affected",
"version": "457b9a6f09f0",
"lessThan": "252a2a5569eb",
"versionType": "git"
},
{
"status": "affected",
"version": "457b9a6f09f0",
"lessThan": "7e7a0d86542b",
"versionType": "git"
},
{
"status": "affected",
"version": "457b9a6f09f0",
"lessThan": "98fee5bee97a",
"versionType": "git"
},
{
"status": "affected",
"version": "457b9a6f09f0",
"lessThan": "6696f76c32ff",
"versionType": "git"
},
{
"status": "affected",
"version": "457b9a6f09f0",
"lessThan": "67f16bf2cc16",
"versionType": "git"
},
{
"status": "affected",
"version": "457b9a6f09f0",
"lessThan": "77d210e8db4d",
"versionType": "git"
},
{
"status": "affected",
"version": "457b9a6f09f0",
"lessThan": "9a9ab0d96362",
"versionType": "git"
}
],
"programFiles": [
"drivers/android/binder_alloc.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "2.6.29"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "2.6.29",
"versionType": "custom"
},
{
"status": "unaffected",
"version": "4.19.306",
"versionType": "custom",
"lessThanOrEqual": "4.19.*"
},
{
"status": "unaffected",
"version": "5.4.268",
"versionType": "custom",
"lessThanOrEqual": "5.4.*"
},
{
"status": "unaffected",
"version": "5.10.209",
"versionType": "custom",
"lessThanOrEqual": "5.10.*"
},
{
"status": "unaffected",
"version": "5.15.148",
"versionType": "custom",
"lessThanOrEqual": "5.15.*"
},
{
"status": "unaffected",
"version": "6.1.75",
"versionType": "custom",
"lessThanOrEqual": "6.1.*"
},
{
"status": "unaffected",
"version": "6.6.14",
"versionType": "custom",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.7.2",
"versionType": "custom",
"lessThanOrEqual": "6.7.*"
},
{
"status": "unaffected",
"version": "6.8",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"drivers/android/binder_alloc.c"
],
"defaultStatus": "affected"
}
]
git.kernel.org/stable/c/252a2a5569eb9f8d16428872cc24dea1ac0bb097
git.kernel.org/stable/c/6696f76c32ff67fec26823fc2df46498e70d9bf3
git.kernel.org/stable/c/67f16bf2cc1698fd50e01ee8a2becc5a8e6d3a3e
git.kernel.org/stable/c/77d210e8db4d61d43b2d16df66b1ec46fad2ee01
git.kernel.org/stable/c/7e7a0d86542b0ea903006d3f42f33c4f7ead6918
git.kernel.org/stable/c/95b1d336b0642198b56836b89908d07b9a0c9608
git.kernel.org/stable/c/98fee5bee97ad47b527a997d5786410430d1f0e9
git.kernel.org/stable/c/9a9ab0d963621d9d12199df9817e66982582d5a5
lists.debian.org/debian-lts-announce/2024/06/msg00016.html
lists.debian.org/debian-lts-announce/2024/06/msg00020.html