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Date: Sun, 15 Nov 2015 01:45:45 +0000 From: Ben Hutchings <ben@...adent.org.uk> To: linux-kernel@...r.kernel.org, stable@...r.kernel.org CC: akpm@...ux-foundation.org, "Petr Matousek" <pmatouse@...hat.com>, "David Howells" <dhowells@...hat.com> Subject: [PATCH 3.2 59/60] KEYS: Fix race between key destruction and finding a keyring by name 3.2.73-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: David Howells <dhowells@...hat.com> commit 94c4554ba07adbdde396748ee7ae01e86cf2d8d7 upstream. 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 <pmatouse@...hat.com> Signed-off-by: David Howells <dhowells@...hat.com> [carnil: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings <ben@...adent.org.uk> --- security/keys/gc.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) --- a/security/keys/gc.c +++ b/security/keys/gc.c @@ -172,6 +172,10 @@ static noinline void key_gc_unused_key(s { 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 */ @@ -186,10 +190,6 @@ static noinline void key_gc_unused_key(s 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); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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