Red Hat Security Advisory: kernel security update

Important

A flaw was found in the Linux kernel’s Bluetooth management subsystem (net/bluetooth/mgmt*.c). The mgmt_pending structure may be freed while still being processed, or remain on the pending command list, which allows a use-after-free or double-free scenario. An attacker with local access to the system and the ability to interact with the Bluetooth subsystem could exploit this to trigger memory corruption, potentially leading to elevated privileges or denial of service.

CWE-416 - Use After Free

In the Linux kernel, the following vulnerability has been resolved: ima: don't clear IMA_DIGSIG flag when setting or removing non-IMA xattr Currently when both IMA and EVM are in fix mode, the IMA signature will be reset to IMA hash if a program first stores IMA signature in security.ima and then writes/removes some other security xattr for the file. For example, on Fedora, after booting the kernel with "ima_appraise=fix evm=fix ima_policy=appraise_tcb" and installing rpm-plugin-ima, installing/reinstalling a package will not make good reference IMA signature generated. Instead IMA hash is generated, # getfattr -m - -d -e hex /usr/bin/bash # file: usr/bin/bash security.ima=0x0404... This happens because when setting security.selinux, the IMA_DIGSIG flag that had been set early was cleared. As a result, IMA hash is generated when the file is closed. Similarly, IMA signature can be cleared on file close after removing security xattr like security.evm or setting/removing ACL. Prevent replacing the IMA file signature with a file hash, by preventing the IMA_DIGSIG flag from being reset. Here's a minimal C reproducer which sets security.selinux as the last step which can also replaced by removing security.evm or setting ACL, #include <stdio.h> #include <sys/xattr.h> #include <fcntl.h> #include <unistd.h> #include <string.h> #include <stdlib.h> int main() { const char* file_path = "/usr/sbin/test_binary"; const char* hex_string = "030204d33204490066306402304"; int length = strlen(hex_string); char* ima_attr_value; int fd; fd = open(file_path, O_WRONLY|O_CREAT|O_EXCL, 0644); if (fd == -1) { perror("Error opening file"); return 1; } ima_attr_value = (char*)malloc(length / 2 ); for (int i = 0, j = 0; i < length; i += 2, j++) { sscanf(hex_string + i, "%2hhx", &ima_attr_value[j]); } if (fsetxattr(fd, "security.ima", ima_attr_value, length/2, 0) == -1) { perror("Error setting extended attribute"); close(fd); return 1; } const char* selinux_value= "system_u:object_r:bin_t:s0"; if (fsetxattr(fd, "security.selinux", selinux_value, strlen(selinux_value), 0) == -1) { perror("Error setting extended attribute"); close(fd); return 1; } close(fd); return 0; }

CWE-354 - Improper Validation of Integrity Check Value

In the Linux kernel, the following vulnerability has been resolved: ALSA: firewire-motu: fix buffer overflow in hwdep read for DSP events The DSP event handling code in hwdep_read() could write more bytes to the user buffer than requested, when a user provides a buffer smaller than the event header size (8 bytes). Fix by using min_t() to clamp the copy size, This ensures we never copy more than the user requested.

CWE-787 - Out-of-bounds Write

In the Linux kernel, the following vulnerability has been resolved: libceph: make decode_pool() more resilient against corrupted osdmaps If the osdmap is (maliciously) corrupted such that the encoded length of ceph_pg_pool envelope is less than what is expected for a particular encoding version, out-of-bounds reads may ensue because the only bounds check that is there is based on that length value. This patch adds explicit bounds checks for each field that is decoded or skipped.

CWE-125 - Out-of-bounds Read