From: David Jeffery Date: Wed, 10 Jul 2013 17:19:50 +0000 (-0400) Subject: lockd: protect nlm_blocked access in nlmsvc_retry_blocked X-Git-Tag: v3.2.50~48 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=7f9fd38136b10b94338a9ae1b2d14830f444974e;p=pandora-kernel.git lockd: protect nlm_blocked access in nlmsvc_retry_blocked commit 1c327d962fc420aea046c16215a552710bde8231 upstream. In nlmsvc_retry_blocked, the check that the list is non-empty and acquiring the pointer of the first entry is unprotected by any lock. This allows a rare race condition when there is only one entry on the list. A function such as nlmsvc_grant_callback() can be called, which will temporarily remove the entry from the list. Between the list_empty() and list_entry(),the list may become empty, causing an invalid pointer to be used as an nlm_block, leading to a possible crash. This patch adds the nlm_block_lock around these calls to prevent concurrent use of the nlm_blocked list. This was a regression introduced by f904be9cc77f361d37d71468b13ff3d1a1823dea "lockd: Mostly remove BKL from the server". Cc: Bryan Schumaker Signed-off-by: David Jeffery Signed-off-by: J. Bruce Fields Signed-off-by: Ben Hutchings --- Reading git-diff-tree failed