diff options
Diffstat (limited to 'debian/patches/bugfix/all/nfsd-fix-use-after-free-due-to-delegation-race.patch')
| -rw-r--r-- | debian/patches/bugfix/all/nfsd-fix-use-after-free-due-to-delegation-race.patch | 67 |
1 files changed, 67 insertions, 0 deletions
diff --git a/debian/patches/bugfix/all/nfsd-fix-use-after-free-due-to-delegation-race.patch b/debian/patches/bugfix/all/nfsd-fix-use-after-free-due-to-delegation-race.patch new file mode 100644 index 000000000..34584d8b5 --- /dev/null +++ b/debian/patches/bugfix/all/nfsd-fix-use-after-free-due-to-delegation-race.patch @@ -0,0 +1,67 @@ +From: "J. Bruce Fields" <bfields@redhat.com> +Date: Mon, 29 Nov 2021 15:08:00 -0500 +Subject: nfsd: fix use-after-free due to delegation race +Origin: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/commit?id=148c816f10fd11df27ca6a9b3238cdd42fa72cd3 +Bug-Debian: https://bugs.debian.org/988044 + +commit 548ec0805c399c65ed66c6641be467f717833ab5 upstream. + +A delegation break could arrive as soon as we've called vfs_setlease. A +delegation break runs a callback which immediately (in +nfsd4_cb_recall_prepare) adds the delegation to del_recall_lru. If we +then exit nfs4_set_delegation without hashing the delegation, it will be +freed as soon as the callback is done with it, without ever being +removed from del_recall_lru. + +Symptoms show up later as use-after-free or list corruption warnings, +usually in the laundromat thread. + +I suspect aba2072f4523 "nfsd: grant read delegations to clients holding +writes" made this bug easier to hit, but I looked as far back as v3.0 +and it looks to me it already had the same problem. So I'm not sure +where the bug was introduced; it may have been there from the beginning. + +Cc: stable@vger.kernel.org +Signed-off-by: J. Bruce Fields <bfields@redhat.com> +Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> +--- + fs/nfsd/nfs4state.c | 9 +++++++-- + 1 file changed, 7 insertions(+), 2 deletions(-) + +diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c +index 3f4027a5de88..61301affb4c1 100644 +--- a/fs/nfsd/nfs4state.c ++++ b/fs/nfsd/nfs4state.c +@@ -1207,6 +1207,11 @@ hash_delegation_locked(struct nfs4_delegation *dp, struct nfs4_file *fp) + return 0; + } + ++static bool delegation_hashed(struct nfs4_delegation *dp) ++{ ++ return !(list_empty(&dp->dl_perfile)); ++} ++ + static bool + unhash_delegation_locked(struct nfs4_delegation *dp) + { +@@ -1214,7 +1219,7 @@ unhash_delegation_locked(struct nfs4_delegation *dp) + + lockdep_assert_held(&state_lock); + +- if (list_empty(&dp->dl_perfile)) ++ if (!delegation_hashed(dp)) + return false; + + dp->dl_stid.sc_type = NFS4_CLOSED_DELEG_STID; +@@ -4598,7 +4603,7 @@ static void nfsd4_cb_recall_prepare(struct nfsd4_callback *cb) + * queued for a lease break. Don't queue it again. + */ + spin_lock(&state_lock); +- if (dp->dl_time == 0) { ++ if (delegation_hashed(dp) && dp->dl_time == 0) { + dp->dl_time = ktime_get_boottime_seconds(); + list_add_tail(&dp->dl_recall_lru, &nn->del_recall_lru); + } +-- +2.34.1 + |