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commitc61760e694upstream. Commits8a4cd82d("nfc: fix refcount leak in llcp_sock_connect()") andc33b1cc62("nfc: fix refcount leak in llcp_sock_bind()") fixed a refcount leak bug in bind/connect but introduced a use-after-free if the same local is assigned to 2 different sockets. This can be triggered by the following simple program: int sock1 = socket( AF_NFC, SOCK_STREAM, NFC_SOCKPROTO_LLCP ); int sock2 = socket( AF_NFC, SOCK_STREAM, NFC_SOCKPROTO_LLCP ); memset( &addr, 0, sizeof(struct sockaddr_nfc_llcp) ); addr.sa_family = AF_NFC; addr.nfc_protocol = NFC_PROTO_NFC_DEP; bind( sock1, (struct sockaddr*) &addr, sizeof(struct sockaddr_nfc_llcp) ) bind( sock2, (struct sockaddr*) &addr, sizeof(struct sockaddr_nfc_llcp) ) close(sock1); close(sock2); Fix this by assigning NULL to llcp_sock->local after calling nfc_llcp_local_put. This addresses CVE-2021-23134. Reported-by: Or Cohen <orcohen@paloaltonetworks.com> Reported-by: Nadav Markus <nmarkus@paloaltonetworks.com> Fixes:c33b1cc62("nfc: fix refcount leak in llcp_sock_bind()") Signed-off-by: Or Cohen <orcohen@paloaltonetworks.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.