Description

In the Linux kernel, the following vulnerability has been resolved: net: Drop the lock in skb_may_tx_timestamp() skb_may_tx_timestamp() may acquire sock::sk_callback_lock. The lock must not be taken in IRQ context, only softirq is okay. A few drivers receive the timestamp via a dedicated interrupt and complete the TX timestamp from that handler. This will lead to a deadlock if the lock is already write-locked on the same CPU. Taking the lock can be avoided. The socket (pointed by the skb) will remain valid until the skb is released. The ->sk_socket and ->file member will be set to NULL once the user closes the socket which may happen before the timestamp arrives. If we happen to observe the pointer while the socket is closing but before the pointer is set to NULL then we may use it because both pointer (and the file's cred member) are RCU freed. Drop the lock. Use READ_ONCE() to obtain the individual pointer. Add a matching WRITE_ONCE() where the pointer are cleared.

Weaknesses 1

Affected Products 3

References 3

• git.kernel.org https://git.kernel.org/stable/c/983512f3a87fd8dc4c94dfa6b596b6e57df5aad7
  Patch
• git.kernel.org https://git.kernel.org/stable/c/e4c6efb3b70ff87f1df99efce2f8893717695718
  Patch
• git.kernel.org https://git.kernel.org/stable/c/f3e4cceafad27c9363c33622732f86722846ec6f
  Patch

Remediation

• git.kernel.org https://git.kernel.org/stable/c/983512f3a87fd8dc4c94dfa6b596b6e57df5aad7
  Patch
• git.kernel.org https://git.kernel.org/stable/c/e4c6efb3b70ff87f1df99efce2f8893717695718
  Patch
• git.kernel.org https://git.kernel.org/stable/c/f3e4cceafad27c9363c33622732f86722846ec6f
  Patch