CVSS3
Attack Vector
LOCAL
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
EPSS
Percentile
5.0%
In the Linux kernel, the following vulnerability has been resolved:
usb: f_fs: Fix use-after-free for epfile
Consider a case where ffs_func_eps_disable is called from
ffs_func_disable as part of composition switch and at the
same time ffs_epfile_release get called from userspace.
ffs_epfile_release will free up the read buffer and call
ffs_data_closed which in turn destroys ffs->epfiles and
mark it as NULL. While this was happening the driver has
already initialized the local epfile in ffs_func_eps_disable
which is now freed and waiting to acquire the spinlock. Once
spinlock is acquired the driver proceeds with the stale value
of epfile and tries to free the already freed read buffer
causing use-after-free.
Following is the illustration of the race:
CPU1 CPU2
ffs_func_eps_disable
epfiles (local copy)
ffs_epfile_release
ffs_data_closed
if (last file closed)
ffs_data_reset
ffs_data_clear
ffs_epfiles_destroy
spin_lock
dereference epfiles
Fix this races by taking epfiles local copy & assigning it under
spinlock and if epfiles(local) is null then update it in ffs->epfiles
then finally destroy it.
Extending the scope further from the race, protecting the ep related
structures, and concurrent accesses.
Vendor | Product | Version | CPE |
---|---|---|---|
linux | linux_kernel | * | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
git.kernel.org/stable/c/0042178a69eb77a979e36a50dcce9794a3140ef8
git.kernel.org/stable/c/32048f4be071f9a6966744243f1786f45bb22dc2
git.kernel.org/stable/c/3e078b18753669615301d946297bafd69294ad2c
git.kernel.org/stable/c/72a8aee863af099d4434314c4536d6c9a61dcf3c
git.kernel.org/stable/c/c9fc422c9a43e3d58d246334a71f3390401781dc
git.kernel.org/stable/c/cfe5f6fd335d882bcc829a1c8a7d462a455c626e
git.kernel.org/stable/c/ebe2b1add1055b903e2acd86b290a85297edc0b3