From 0856d72c31760ae2ef274242f5e65aa8543ed6e7 Mon Sep 17 00:00:00 2001 From: Salvatore Bonaccorso Date: Mon, 19 Oct 2015 21:22:47 +0200 Subject: [PATCH] KEYS: Fix race between key destruction and finding a keyring by name --- debian/changelog | 6 +++ ...tween-key-destruction-and-finding-a-.patch | 52 +++++++++++++++++++ debian/patches/series | 2 + 3 files changed, 60 insertions(+) create mode 100644 debian/patches/bugfix/all/0001-KEYS-Fix-race-between-key-destruction-and-finding-a-.patch diff --git a/debian/changelog b/debian/changelog index e014cd62a..689cc9922 100644 --- a/debian/changelog +++ b/debian/changelog @@ -1,3 +1,9 @@ +linux (4.2.3-3) UNRELEASED; urgency=medium + + * KEYS: Fix race between key destruction and finding a keyring by name + + -- Salvatore Bonaccorso Mon, 19 Oct 2015 21:23:18 +0200 + linux (4.2.3-2) unstable; urgency=medium * nbd: Restore request timeout detection (Closes: #770479) diff --git a/debian/patches/bugfix/all/0001-KEYS-Fix-race-between-key-destruction-and-finding-a-.patch b/debian/patches/bugfix/all/0001-KEYS-Fix-race-between-key-destruction-and-finding-a-.patch new file mode 100644 index 000000000..3e779c303 --- /dev/null +++ b/debian/patches/bugfix/all/0001-KEYS-Fix-race-between-key-destruction-and-finding-a-.patch @@ -0,0 +1,52 @@ +From: David Howells +Date: Fri, 25 Sep 2015 16:30:08 +0100 +Subject: KEYS: Fix race between key destruction and finding a keyring by name +Origin: https://git.kernel.org/linus/94c4554ba07adbdde396748ee7ae01e86cf2d8d7 + +There appears to be a race between: + + (1) key_gc_unused_keys() which frees key->security and then calls + keyring_destroy() to unlink the name from the name list + + (2) find_keyring_by_name() which calls key_permission(), thus accessing + key->security, on a key before checking to see whether the key usage is 0 + (ie. the key is dead and might be cleaned up). + +Fix this by calling ->destroy() before cleaning up the core key data - +including key->security. + +Reported-by: Petr Matousek +Signed-off-by: David Howells +--- + security/keys/gc.c | 8 ++++---- + 1 file changed, 4 insertions(+), 4 deletions(-) + +diff --git a/security/keys/gc.c b/security/keys/gc.c +index c795237..39eac1f 100644 +--- a/security/keys/gc.c ++++ b/security/keys/gc.c +@@ -134,6 +134,10 @@ static noinline void key_gc_unused_keys(struct list_head *keys) + kdebug("- %u", key->serial); + key_check(key); + ++ /* Throw away the key data */ ++ if (key->type->destroy) ++ key->type->destroy(key); ++ + security_key_free(key); + + /* deal with the user's key tracking and quota */ +@@ -148,10 +152,6 @@ static noinline void key_gc_unused_keys(struct list_head *keys) + if (test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) + atomic_dec(&key->user->nikeys); + +- /* now throw away the key memory */ +- if (key->type->destroy) +- key->type->destroy(key); +- + key_user_put(key->user); + + kfree(key->description); +-- +2.6.1 + diff --git a/debian/patches/series b/debian/patches/series index c7350cf35..46ea6dbff 100644 --- a/debian/patches/series +++ b/debian/patches/series @@ -107,3 +107,5 @@ bugfix/x86/crypto-x86-camellia_aesni_avx-fix-cpu-feature-checks.patch bugfix/all/nbd-fix-timeout-detection.patch bugfix/all/nbd-remove-variable-pid.patch bugfix/all/nbd-add-locking-for-tasks.patch + +bugfix/all/0001-KEYS-Fix-race-between-key-destruction-and-finding-a-.patch