In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
smb: client: fix request buffer leak in smb2_new_read_req()<\/p>\n
smb2_new_read_req() allocates the request buffer with
\nsmb2_plain_req_init() but only publishes it to the caller with
\n*buf = req at the very end of the function. Two error returns sit in
\nbetween:<\/p>\n
\trc = smb2_plain_req_init(SMB2_READ, io_parms->tcon, server,
\n\t\t\t\t (void **) &req, total_len);
\n\tif (rc)
\n\t\treturn rc;<\/p>\n
\tif (server == NULL)
\n\t\treturn -ECONNABORTED;
\n\t[…]
\n\t\trdata->mr = smbd_register_mr(server->smbd_conn,
\n\t\t\t\t\t &rdata->subreq.io_iter,
\n\t\t\t\t\t true, need_invalidate);
\n\t\tif (!rdata->mr)
\n\t\t\treturn -EAGAIN;<\/p>\n
On either of them the buffer is neither released nor handed back, so
\nit is leaked. The caller cannot clean up after it: smb2_async_readv()
\ndoes ‘goto out’ on a non-zero return, which skips the
\ncifs_small_buf_release(buf) at async_readv_out, and buf has not been
\nassigned at that point in any case.<\/p>\n
The write path has never had this problem. smb2_async_writev()
\nregisters the memory region inline and jumps to its release label
\ninstead of returning:<\/p>\n
\twdata->mr = smbd_register_mr(…);
\n\tif (!wdata->mr) {
\n\t\trc = -EAGAIN;
\n\t\tgoto async_writev_out;
\n\t}<\/p>\n
Commit b7972092199f (“cifs: smbd: Retry on memory registration
\nfailure”) changed both sides from -ENOBUFS to -EAGAIN in a single
\npatch, which puts the two shapes next to each other.<\/p>\n
Only the -EAGAIN return is reachable in practice, because
\nsmb2_plain_req_init() calls smb2_reconnect() first and that already
\nfails with -EIO when server is NULL, before anything is allocated.
\nBoth returns are given the same treatment here rather than leaving
\none of them correct only by accident.<\/p>\n
Because -EAGAIN is a replayable error, the failure also reaches the
\nretry block at the end of smb2_async_readv(), which marks the
\nsubrequest NETFS_SREQ_NEED_RETRY, so a failing registration can be
\nretried rather than ending the I\/O, and every attempt that reaches it
\nleaks another buffer. smb2_should_replay() short-circuits on
\ntcon->retry, so on a hard mount the attempt count is not bounded by
\nthe retrans setting.<\/p>\n
Only the asynchronous read path is affected. The synchronous
\nSMB2_read() caller passes rdata == NULL and the memory registration
\nblock is guarded on rdata.<\/p>\n
The memory registration failure path was pointed out by the Sashiko
\nAI reviewer while it was reviewing an unrelated patch to
\nsmb2_async_readv().<\/p>\n","protected":false},"excerpt":{"rendered":"
In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
smb: client: fix request buffer leak in smb2_new_read_req()<\/p>\n
smb2_new_read_req() allocates the request buffer with
\nsmb2_plain_req_i<\/p>\n","protected":false},"template":"","meta":[],"categories":[],"tags":[],"class_list":["post-25534","vuln","type-vuln","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln\/25534","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln"}],"about":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/types\/vuln"}],"wp:attachment":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=25534"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=25534"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=25534"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}