RHSA-2023:6901

There is an infoleak vulnerability in the Linux kernel's net/bluetooth/l2cap_core.c's l2cap_parse_conf_req function which can be used to leak kernel pointers remotely. We recommend upgrading past commit  https://github.com/torvalds/linux/commit/b1a2cd50c0357f243b7435a732b4e62ba3157a2e https://www.google.com/url

A flaw use after free in the Linux kernel integrated infrared receiver/transceiver driver was found in the way user detaching rc device. A local user could use this flaw to crash the system or potentially escalate their privileges on the system.

A use-after-free flaw was found in xgene_hwmon_remove in drivers/hwmon/xgene-hwmon.c in the Hardware Monitoring Linux Kernel Driver (xgene-hwmon). This flaw could allow a local attacker to crash the system due to a race problem. This vulnerability could even lead to a kernel information leak problem.

The Linux kernel allows userspace processes to enable mitigations by calling prctl with PR_SET_SPECULATION_CTRL which disables the speculation feature as well as by using seccomp. We had noticed that on VMs of at least one major cloud provider, the kernel still left the victim process exposed to attacks in some cases even after enabling the spectre-BTI mitigation with prctl. The same behavior can be observed on a bare-metal machine when forcing the mitigation to IBRS on boot command line. This happened because when plain IBRS was enabled (not enhanced IBRS), the kernel had some logic that determined that STIBP was not needed. The IBRS bit implicitly protects against cross-thread branch target injection. However, with legacy IBRS, the IBRS bit was cleared on returning to userspace, due to performance reasons, which disabled the implicit STIBP and left userspace threads vulnerable to cross-thread branch target injection against which STIBP protects.

A use-after-free vulnerability was found in the Linux kernel's ext4 filesystem in the way it handled the extra inode size for extended attributes. This flaw could allow a privileged local user to cause a system crash or other undefined behaviors.

A flaw was found in the Framebuffer Console (fbcon) in the Linux Kernel. When providing font->width and font->height greater than 32 to fbcon_set_font, since there are no checks in place, a shift-out-of-bounds occurs leading to undefined behavior and possible denial of service.

A NULL pointer dereference issue was found in the gfs2 file system in the Linux kernel. It occurs on corrupt gfs2 file systems when the evict code tries to reference the journal descriptor structure after it has been freed and set to NULL. A privileged local user could use this flaw to cause a kernel panic.