diff options
Diffstat (limited to 'meta/recipes-devtools/qemu/qemu/CVE-2020-10761.patch')
| -rw-r--r-- | meta/recipes-devtools/qemu/qemu/CVE-2020-10761.patch | 151 |
1 files changed, 0 insertions, 151 deletions
diff --git a/meta/recipes-devtools/qemu/qemu/CVE-2020-10761.patch b/meta/recipes-devtools/qemu/qemu/CVE-2020-10761.patch deleted file mode 100644 index 19f26ae5b0..0000000000 --- a/meta/recipes-devtools/qemu/qemu/CVE-2020-10761.patch +++ /dev/null @@ -1,151 +0,0 @@ -From 5c4fe018c025740fef4a0a4421e8162db0c3eefd Mon Sep 17 00:00:00 2001 -From: Eric Blake <eblake@redhat.com> -Date: Mon, 8 Jun 2020 13:26:37 -0500 -Subject: [PATCH] nbd/server: Avoid long error message assertions - CVE-2020-10761 - -Ever since commit 36683283 (v2.8), the server code asserts that error -strings sent to the client are well-formed per the protocol by not -exceeding the maximum string length of 4096. At the time the server -first started sending error messages, the assertion could not be -triggered, because messages were completely under our control. -However, over the years, we have added latent scenarios where a client -could trigger the server to attempt an error message that would -include the client's information if it passed other checks first: - -- requesting NBD_OPT_INFO/GO on an export name that is not present - (commit 0cfae925 in v2.12 echoes the name) - -- requesting NBD_OPT_LIST/SET_META_CONTEXT on an export name that is - not present (commit e7b1948d in v2.12 echoes the name) - -At the time, those were still safe because we flagged names larger -than 256 bytes with a different message; but that changed in commit -93676c88 (v4.2) when we raised the name limit to 4096 to match the NBD -string limit. (That commit also failed to change the magic number -4096 in nbd_negotiate_send_rep_err to the just-introduced named -constant.) So with that commit, long client names appended to server -text can now trigger the assertion, and thus be used as a denial of -service attack against a server. As a mitigating factor, if the -server requires TLS, the client cannot trigger the problematic paths -unless it first supplies TLS credentials, and such trusted clients are -less likely to try to intentionally crash the server. - -We may later want to further sanitize the user-supplied strings we -place into our error messages, such as scrubbing out control -characters, but that is less important to the CVE fix, so it can be a -later patch to the new nbd_sanitize_name. - -Consideration was given to changing the assertion in -nbd_negotiate_send_rep_verr to instead merely log a server error and -truncate the message, to avoid leaving a latent path that could -trigger a future CVE DoS on any new error message. However, this -merely complicates the code for something that is already (correctly) -flagging coding errors, and now that we are aware of the long message -pitfall, we are less likely to introduce such errors in the future, -which would make such error handling dead code. - -Reported-by: Xueqiang Wei <xuwei@redhat.com> -CC: qemu-stable@nongnu.org -Fixes: https://bugzilla.redhat.com/1843684 CVE-2020-10761 -Fixes: 93676c88d7 -Signed-off-by: Eric Blake <eblake@redhat.com> -Message-Id: <20200610163741.3745251-2-eblake@redhat.com> -Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> - -Upstream-Status: Backport [https://github.com/qemu/qemu/commit/5c4fe018c025740fef4a0a4421e8162db0c3eefd] -CVE: CVE-2020-10761 -Signed-off-by: Chee Yang Lee <chee.yang.lee@intel.com> - ---- - nbd/server.c | 23 ++++++++++++++++++++--- - tests/qemu-iotests/143 | 4 ++++ - tests/qemu-iotests/143.out | 2 ++ - 3 files changed, 26 insertions(+), 3 deletions(-) - -diff --git a/nbd/server.c b/nbd/server.c -index 02b1ed08014..20754e9ebc3 100644 ---- a/nbd/server.c -+++ b/nbd/server.c -@@ -217,7 +217,7 @@ nbd_negotiate_send_rep_verr(NBDClient *client, uint32_t type, - - msg = g_strdup_vprintf(fmt, va); - len = strlen(msg); -- assert(len < 4096); -+ assert(len < NBD_MAX_STRING_SIZE); - trace_nbd_negotiate_send_rep_err(msg); - ret = nbd_negotiate_send_rep_len(client, type, len, errp); - if (ret < 0) { -@@ -231,6 +231,19 @@ nbd_negotiate_send_rep_verr(NBDClient *client, uint32_t type, - return 0; - } - -+/* -+ * Return a malloc'd copy of @name suitable for use in an error reply. -+ */ -+static char * -+nbd_sanitize_name(const char *name) -+{ -+ if (strnlen(name, 80) < 80) { -+ return g_strdup(name); -+ } -+ /* XXX Should we also try to sanitize any control characters? */ -+ return g_strdup_printf("%.80s...", name); -+} -+ - /* Send an error reply. - * Return -errno on error, 0 on success. */ - static int GCC_FMT_ATTR(4, 5) -@@ -595,9 +608,11 @@ static int nbd_negotiate_handle_info(NBDClient *client, Error **errp) - - exp = nbd_export_find(name); - if (!exp) { -+ g_autofree char *sane_name = nbd_sanitize_name(name); -+ - return nbd_negotiate_send_rep_err(client, NBD_REP_ERR_UNKNOWN, - errp, "export '%s' not present", -- name); -+ sane_name); - } - - /* Don't bother sending NBD_INFO_NAME unless client requested it */ -@@ -995,8 +1010,10 @@ static int nbd_negotiate_meta_queries(NBDClient *client, - - meta->exp = nbd_export_find(export_name); - if (meta->exp == NULL) { -+ g_autofree char *sane_name = nbd_sanitize_name(export_name); -+ - return nbd_opt_drop(client, NBD_REP_ERR_UNKNOWN, errp, -- "export '%s' not present", export_name); -+ "export '%s' not present", sane_name); - } - - ret = nbd_opt_read(client, &nb_queries, sizeof(nb_queries), errp); -diff --git a/tests/qemu-iotests/143 b/tests/qemu-iotests/143 -index f649b361950..d2349903b1b 100755 ---- a/tests/qemu-iotests/143 -+++ b/tests/qemu-iotests/143 -@@ -58,6 +58,10 @@ _send_qemu_cmd $QEMU_HANDLE \ - $QEMU_IO_PROG -f raw -c quit \ - "nbd+unix:///no_such_export?socket=$SOCK_DIR/nbd" 2>&1 \ - | _filter_qemu_io | _filter_nbd -+# Likewise, with longest possible name permitted in NBD protocol -+$QEMU_IO_PROG -f raw -c quit \ -+ "nbd+unix:///$(printf %4096d 1 | tr ' ' a)?socket=$SOCK_DIR/nbd" 2>&1 \ -+ | _filter_qemu_io | _filter_nbd | sed 's/aaaa*aa/aa--aa/' - - _send_qemu_cmd $QEMU_HANDLE \ - "{ 'execute': 'quit' }" \ -diff --git a/tests/qemu-iotests/143.out b/tests/qemu-iotests/143.out -index 1f4001c6013..fc9c0a761fa 100644 ---- a/tests/qemu-iotests/143.out -+++ b/tests/qemu-iotests/143.out -@@ -5,6 +5,8 @@ QA output created by 143 - {"return": {}} - qemu-io: can't open device nbd+unix:///no_such_export?socket=SOCK_DIR/nbd: Requested export not available - server reported: export 'no_such_export' not present -+qemu-io: can't open device nbd+unix:///aa--aa1?socket=SOCK_DIR/nbd: Requested export not available -+server reported: export 'aa--aa...' not present - { 'execute': 'quit' } - {"return": {}} - {"timestamp": {"seconds": TIMESTAMP, "microseconds": TIMESTAMP}, "event": "SHUTDOWN", "data": {"guest": false, "reason": "host-qmp-quit"}} |