Bug 2513428 (CVE-2026-68158)

Summary: CVE-2026-68158 kernel: libceph: Fix multiplication overflow in decode_new_up_state_weight()
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
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Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
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Hardware: All   
OS: Linux   
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A flaw was found in `libceph` within the Linux kernel. A remote attacker could send a maliciously crafted `CEPH_MSG_OSD_MAP` message, leading to a multiplication overflow in the `decode_new_up_state_weight()` function. This overflow causes an incorrect bounds check, which may result in out-of-bounds memory reads. This could potentially lead to information disclosure or system instability.
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Description OSIDB Bzimport 2026-08-10 12:36:47 UTC 
In the Linux kernel, the following vulnerability has been resolved:

libceph: Fix multiplication overflow in decode_new_up_state_weight()

If a message of type CEPH_MSG_OSD_MAP contains a (maliciously) corrupted
osdmap, out-of-bounds memory accesses may occur in
decode_new_up_state_weight(). This happens because the bounds check for
the new_state part is based on calculating its length depending on a len
value read from the incoming message. This calculation may overflow
leading to an incorrect bounds check. Subsequently, out-of-bounds reads
may occur when decoding this part.

This patch switches the multiplication to use check_mul_overflow() to
abort processing the osdmap if an overflow occurred. Therefore,
osdmaps/messages containing large values for len that result in a
multiplication overflow are treated as invalid.

[ idryomov: rename new_state_len -> new_state_item_size, formatting ]
Comment 1 Mauro Matteo Cascella 2026-08-11 12:58:20 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026081003-CVE-2026-68158-1af0@gregkh/T