From 1c327d962fc420aea046c16215a552710bde8231 Mon Sep 17 00:00:00 2001 From: David Jeffery Date: Wed, 10 Jul 2013 13:19:50 -0400 Subject: lockd: protect nlm_blocked access in nlmsvc_retry_blocked 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 Cc: stable@vger.kernel.org Signed-off-by: David Jeffery Signed-off-by: J. Bruce Fields --- fs/lockd/svclock.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'fs') diff --git a/fs/lockd/svclock.c b/fs/lockd/svclock.c index e703318c41df..8ebd3f551e0c 100644 --- a/fs/lockd/svclock.c +++ b/fs/lockd/svclock.c @@ -939,6 +939,7 @@ nlmsvc_retry_blocked(void) unsigned long timeout = MAX_SCHEDULE_TIMEOUT; struct nlm_block *block; + spin_lock(&nlm_blocked_lock); while (!list_empty(&nlm_blocked) && !kthread_should_stop()) { block = list_entry(nlm_blocked.next, struct nlm_block, b_list); @@ -948,6 +949,7 @@ nlmsvc_retry_blocked(void) timeout = block->b_when - jiffies; break; } + spin_unlock(&nlm_blocked_lock); dprintk("nlmsvc_retry_blocked(%p, when=%ld)\n", block, block->b_when); @@ -957,7 +959,9 @@ nlmsvc_retry_blocked(void) retry_deferred_block(block); } else nlmsvc_grant_blocked(block); + spin_lock(&nlm_blocked_lock); } + spin_unlock(&nlm_blocked_lock); return timeout; } -- cgit v1.2.3 From 35f7a14fc1180164d6358a5885031fc187ef1bfa Mon Sep 17 00:00:00 2001 From: "J. Bruce Fields" Date: Mon, 8 Jul 2013 19:51:44 -0400 Subject: nfsd4: fix minorversion support interface You can turn on or off support for minorversions using e.g. echo "-4.2" >/proc/fs/nfsd/versions However, the current implementation is a little wonky. For example, the above will turn off 4.2 support, but it will also turn *on* 4.1 support. This didn't matter as long as we only had 2 minorversions, which was true till very recently. And do a little cleanup here. Signed-off-by: J. Bruce Fields --- fs/nfsd/nfs4proc.c | 2 +- fs/nfsd/nfsd.h | 1 - fs/nfsd/nfssvc.c | 13 +++++++------ 3 files changed, 8 insertions(+), 8 deletions(-) (limited to 'fs') diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c index a7cee864e7b2..0d4c410e4589 100644 --- a/fs/nfsd/nfs4proc.c +++ b/fs/nfsd/nfs4proc.c @@ -1293,7 +1293,7 @@ nfsd4_proc_compound(struct svc_rqst *rqstp, * According to RFC3010, this takes precedence over all other errors. */ status = nfserr_minor_vers_mismatch; - if (args->minorversion > nfsd_supported_minorversion) + if (nfsd_minorversion(args->minorversion, NFSD_TEST) <= 0) goto out; status = nfs41_check_op_ordering(args); diff --git a/fs/nfsd/nfsd.h b/fs/nfsd/nfsd.h index 2bbd94e51efc..30f34ab02137 100644 --- a/fs/nfsd/nfsd.h +++ b/fs/nfsd/nfsd.h @@ -53,7 +53,6 @@ struct readdir_cd { extern struct svc_program nfsd_program; extern struct svc_version nfsd_version2, nfsd_version3, nfsd_version4; -extern u32 nfsd_supported_minorversion; extern struct mutex nfsd_mutex; extern spinlock_t nfsd_drc_lock; extern unsigned long nfsd_drc_max_mem; diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c index 6b9f48ca4c25..760c85a6f534 100644 --- a/fs/nfsd/nfssvc.c +++ b/fs/nfsd/nfssvc.c @@ -116,7 +116,10 @@ struct svc_program nfsd_program = { }; -u32 nfsd_supported_minorversion = 1; +static bool nfsd_supported_minorversions[NFSD_SUPPORTED_MINOR_VERSION + 1] = { + [0] = 1, + [1] = 1, +}; int nfsd_vers(int vers, enum vers_op change) { @@ -151,15 +154,13 @@ int nfsd_minorversion(u32 minorversion, enum vers_op change) return -1; switch(change) { case NFSD_SET: - nfsd_supported_minorversion = minorversion; + nfsd_supported_minorversions[minorversion] = true; break; case NFSD_CLEAR: - if (minorversion == 0) - return -1; - nfsd_supported_minorversion = minorversion - 1; + nfsd_supported_minorversions[minorversion] = false; break; case NFSD_TEST: - return minorversion <= nfsd_supported_minorversion; + return nfsd_supported_minorversions[minorversion]; case NFSD_AVAIL: return minorversion <= NFSD_SUPPORTED_MINOR_VERSION; } -- cgit v1.2.3