In the Linux kernel, the following vulnerability has been resolved:
sctp: hold socket lock when dumping endpoints in sctp_diag
SCTP_DIAG endpoint dumping was traversing endpoint address lists without holding lock_sock(), while those lists could change concurrently via socket operations (e.g., bindx changes). This creates a race where nla_reserve() counts addresses under RCU protection, but the subsequent copy may see fewer entries, potentially leaking uninitialized memory to userspace.
Fix this by:
- Taking a reference on each endpoint during hash traversal
- Moving socket operations (lock_sock()) outside read_lock_bh()
- Serializing address list access during dump
- Reworking sctp_for_each_endpoint() to support restart-based traversal with (net, pos) tracking
Also:
- Add WARN_ON_ONCE() for inconsistent address counts
- Fix idiag_states filtering for LISTEN vs association cases
- Skip dumping endpoints being freed (ep->base.dead)
- Move dump position tracking into iterator, removing cb->args[4] and its comment for sctp_ep_dump().,
- Update the comment for cb->args[4] and remove the comment for unused cb->args[5] for sctp_sock_dump().
Note: traversal is restart-based and may re-scan buckets multiple times, but this is acceptable due to small bucket sizes and required to support sleeping-safe callbacks.
This issue was reported by Nico Yip (@cyeaa) working with TrendAI Zero Day Initiative.
References
- https://git.kernel.org/stable/c/207bb4ce8fe7de961ae7bb33569ad2cd61f44954
- https://git.kernel.org/stable/c/722576aba0a6d9423714550b1c03239b0f0def77
- https://git.kernel.org/stable/c/7d8297e26b4e20b5d1c3c3fe51fe81a1c7fbc823
- https://git.kernel.org/stable/c/8b38e3dcfde3077dbc03eb8ef88e03cc19f70b8a
- https://git.kernel.org/stable/c/abe7f8828e6ac8be858870c2bf836258844f97d5
- https://git.kernel.org/stable/c/ec3c2d59a192e17e1014ba71afc368ba162ecac3
- https://git.kernel.org/stable/c/f09a245f33e567b604efa1960b7a2d25dd9c8713
- https://git.kernel.org/stable/c/f98c294a9369b6fe89e652c06357ee594be4dfa2