tun: add missing verification for short frame #172
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jira VULN-8272 cve CVE-2024-41091 commit-author Dongli Zhang <[email protected]> commit 0495848 The cited commit missed to check against the validity of the frame length in the tun_xdp_one() path, which could cause a corrupted skb to be sent downstack. Even before the skb is transmitted, the tun_xdp_one-->eth_type_trans() may access the Ethernet header although it can be less than ETH_HLEN. Once transmitted, this could either cause out-of-bound access beyond the actual length, or confuse the underlayer with incorrect or inconsistent header length in the skb metadata. In the alternative path, tun_get_user() already prohibits short frame which has the length less than Ethernet header size from being transmitted for IFF_TAP. This is to drop any frame shorter than the Ethernet header size just like how tun_get_user() does. CVE: CVE-2024-41091 Inspired-by: https://lore.kernel.org/netdev/[email protected]/ Fixes: 043d222 ("tuntap: accept an array of XDP buffs through sendmsg()") Cc: [email protected] Signed-off-by: Dongli Zhang <[email protected]> Reviewed-by: Si-Wei Liu <[email protected]> Reviewed-by: Willem de Bruijn <[email protected]> Reviewed-by: Paolo Abeni <[email protected]> Reviewed-by: Jason Wang <[email protected]> Link: https://patch.msgid.link/[email protected] Signed-off-by: Jakub Kicinski <[email protected]> (cherry picked from commit 0495848) Signed-off-by: Jeremy Allison <[email protected]>
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jira VULN-8272
cve CVE-2024-41091
commit-author Dongli Zhang [email protected] commit 0495848
The cited commit missed to check against the validity of the frame length in the tun_xdp_one() path, which could cause a corrupted skb to be sent downstack. Even before the skb is transmitted, the tun_xdp_one-->eth_type_trans() may access the Ethernet header although it can be less than ETH_HLEN. Once transmitted, this could either cause out-of-bound access beyond the actual length, or confuse the underlayer with incorrect or inconsistent header length in the skb metadata.
In the alternative path, tun_get_user() already prohibits short frame which has the length less than Ethernet header size from being transmitted for IFF_TAP.
This is to drop any frame shorter than the Ethernet header size just like how tun_get_user() does.
CVE: CVE-2024-41091
Inspired-by: https://lore.kernel.org/netdev/[email protected]/ Fixes: 043d222 ("tuntap: accept an array of XDP buffs through sendmsg()")
Cc: [email protected]
Signed-off-by: Dongli Zhang [email protected]
Reviewed-by: Si-Wei Liu [email protected]
Reviewed-by: Willem de Bruijn [email protected]
Reviewed-by: Paolo Abeni [email protected]
Reviewed-by: Jason Wang [email protected]
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski [email protected]
(cherry picked from commit 0495848)
Signed-off-by: Jeremy Allison [email protected]
$ uname -a
Linux r8_6_lts 4.18.0-ciqlts8_6+ #1 SMP Thu Mar 20 18:36:43 UTC 2025 x86_64 x86_64 x86_64 GNU/Linux
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baseline_selftest.txt
patched_selftest.txt
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