Red Hat Security Advisory: kernel security, bug fix, and enhancement update

Important

In the Linux kernel, the following vulnerability has been resolved: xfrm: Duplicate SPI Handling The issue originates when Strongswan initiates an XFRM_MSG_ALLOCSPI Netlink message, which triggers the kernel function xfrm_alloc_spi(). This function is expected to ensure uniqueness of the Security Parameter Index (SPI) for inbound Security Associations (SAs). However, it can return success even when the requested SPI is already in use, leading to duplicate SPIs assigned to multiple inbound SAs, differentiated only by their destination addresses. This behavior causes inconsistencies during SPI lookups for inbound packets. Since the lookup may return an arbitrary SA among those with the same SPI, packet processing can fail, resulting in packet drops. According to RFC 4301 section 4.4.2 , for inbound processing a unicast SA is uniquely identified by the SPI and optionally protocol. Reproducing the Issue Reliably: To consistently reproduce the problem, restrict the available SPI range in charon.conf : spi_min = 0x10000000 spi_max = 0x10000002 This limits the system to only 2 usable SPI values. Next, create more than 2 Child SA. each using unique pair of src/dst address. As soon as the 3rd Child SA is initiated, it will be assigned a duplicate SPI, since the SPI pool is already exhausted. With a narrow SPI range, the issue is consistently reproducible. With a broader/default range, it becomes rare and unpredictable. Current implementation: xfrm_spi_hash() lookup function computes hash using daddr, proto, and family. So if two SAs have the same SPI but different destination addresses, then they will: a. Hash into different buckets b. Be stored in different linked lists (byspi + h) c. Not be seen in the same hlist_for_each_entry_rcu() iteration. As a result, the lookup will result in NULL and kernel allows that Duplicate SPI Proposed Change: xfrm_state_lookup_spi_proto() does a truly global search - across all states, regardless of hash bucket and matches SPI and proto.

CWE-703 - Improper Check or Handling of Exceptional Conditions

In the Linux kernel, the following vulnerability has been resolved: lib/buildid: use __kernel_read() for sleepable context Prevent a "BUG: unable to handle kernel NULL pointer dereference in filemap_read_folio". For the sleepable context, convert freader to use __kernel_read() instead of direct page cache access via read_cache_folio(). This simplifies the faultable code path by using the standard kernel file reading interface which handles all the complexity of reading file data. At the moment we are not changing the code for non-sleepable context which uses filemap_get_folio() and only succeeds if the target folios are already in memory and up-to-date. The reason is to keep the patch simple and easier to backport to stable kernels. Syzbot repro does not crash the kernel anymore and the selftests run successfully. In the follow up we will make __kernel_read() with IOCB_NOWAIT work for non-sleepable contexts. In addition, I would like to replace the secretmem check with a more generic approach and will add fstest for the buildid code.

CWE-476 - NULL Pointer Dereference

A flaw was found in the Linux kernel's futex subsystem. The need_futex_hash_allocate_default() function incorrectly relies on CLONE_THREAD semantics, which can lead to non-concurrency issues when memory allocations (mm->futex_ref pcpu allocations) are shared across CLONE_VM clones, excluding vfork(). This can result in a use-after-free vulnerability in futex_hash_put, a form of memory corruption. Such vulnerabilities can potentially lead to system instability or other security impacts.

CWE-825 - Expired Pointer Dereference