38faa2b546
* gnu/packages/patches/qemu-CVE-2017-15118.patch, gnu/packages/patches/qemu-CVE-2017-15119.patch: New files. * gnu/local.mk (dist_patch_DATA): Add them. * gnu/packages/virtualization.scm (qemu)[source]: Use them.
68 lines
2.6 KiB
Diff
68 lines
2.6 KiB
Diff
Fix CVE-2017-15119:
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https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2017-15119
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https://bugzilla.redhat.com/show_bug.cgi?id=1516925
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Patch copied from upstream source repository:
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https://git.qemu.org/?p=qemu.git;a=commitdiff;h=fdad35ef6c5839d50dfc14073364ac893afebc30
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From fdad35ef6c5839d50dfc14073364ac893afebc30 Mon Sep 17 00:00:00 2001
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From: Eric Blake <eblake@redhat.com>
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Date: Wed, 22 Nov 2017 16:25:16 -0600
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Subject: [PATCH] nbd/server: CVE-2017-15119 Reject options larger than 32M
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The NBD spec gives us permission to abruptly disconnect on clients
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that send outrageously large option requests, rather than having
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to spend the time reading to the end of the option. No real
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option request requires that much data anyways; and meanwhile, we
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already have the practice of abruptly dropping the connection on
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any client that sends NBD_CMD_WRITE with a payload larger than 32M.
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For comparison, nbdkit drops the connection on any request with
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more than 4096 bytes; however, that limit is probably too low
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(as the NBD spec states an export name can theoretically be up
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to 4096 bytes, which means a valid NBD_OPT_INFO could be even
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longer) - even if qemu doesn't permit exports longer than 256
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bytes.
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It could be argued that a malicious client trying to get us to
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read nearly 4G of data on a bad request is a form of denial of
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service. In particular, if the server requires TLS, but a client
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that does not know the TLS credentials sends any option (other
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than NBD_OPT_STARTTLS or NBD_OPT_EXPORT_NAME) with a stated
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payload of nearly 4G, then the server was keeping the connection
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alive trying to read all the payload, tying up resources that it
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would rather be spending on a client that can get past the TLS
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handshake. Hence, this warranted a CVE.
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Present since at least 2.5 when handling known options, and made
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worse in 2.6 when fixing support for NBD_FLAG_C_FIXED_NEWSTYLE
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to handle unknown options.
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CC: qemu-stable@nongnu.org
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Signed-off-by: Eric Blake <eblake@redhat.com>
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---
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nbd/server.c | 6 ++++++
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1 file changed, 6 insertions(+)
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diff --git a/nbd/server.c b/nbd/server.c
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index 7d6801b427..a81801e3bc 100644
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--- a/nbd/server.c
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+++ b/nbd/server.c
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@@ -673,6 +673,12 @@ static int nbd_negotiate_options(NBDClient *client, uint16_t myflags,
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}
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length = be32_to_cpu(length);
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+ if (length > NBD_MAX_BUFFER_SIZE) {
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+ error_setg(errp, "len (%" PRIu32" ) is larger than max len (%u)",
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+ length, NBD_MAX_BUFFER_SIZE);
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+ return -EINVAL;
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+ }
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+
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trace_nbd_negotiate_options_check_option(option,
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nbd_opt_lookup(option));
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if (client->tlscreds &&
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--
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2.15.0
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