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[net-next,3/4] net: hdlc_fr: Improve the initial check when we receive an skb

Message ID 20201028105705.460551-4-xie.he.0141@gmail.com
State Changes Requested
Delegated to: David Miller
Headers show
Series net: hdlc_fr: Add support for any Ethertype | expand

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Context Check Description
jkicinski/patch_count success Link
jkicinski/cover_letter success Link
jkicinski/fixes_present success Link
jkicinski/tree_selection success Clearly marked for net-next
jkicinski/subject_prefix success Link
jkicinski/source_inline success Was 0 now: 0
jkicinski/verify_signedoff success Link
jkicinski/module_param success Was 0 now: 0
jkicinski/build_32bit fail Errors and warnings before: 4 this patch: 4
jkicinski/kdoc success Errors and warnings before: 0 this patch: 0
jkicinski/verify_fixes success Link
jkicinski/checkpatch fail Link
jkicinski/build_allmodconfig_warn success Errors and warnings before: 0 this patch: 0
jkicinski/header_inline success Link
jkicinski/stable success Stable not CCed

Commit Message

Xie He Oct. 28, 2020, 10:57 a.m. UTC
1.
Change the skb->len check from "<= 4" to "< 4".
At first we only need to ensure a 4-byte header is present. We indeed
normally need the 5th byte, too, but it'd be more logical and cleaner
to check its existence when we actually need it.

2.
Add an fh->ea2 check to the initial checks in fr_fx. fh->ea2 == 1 means
the second address byte is the final address byte. We only support the
case where the address length is 2 bytes.

Cc: Krzysztof Halasa <khc@pm.waw.pl>
Signed-off-by: Xie He <xie.he.0141@gmail.com>
---
 drivers/net/wan/hdlc_fr.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
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Patch

diff --git a/drivers/net/wan/hdlc_fr.c b/drivers/net/wan/hdlc_fr.c
index ac65f5c435ef..3639c2bfb141 100644
--- a/drivers/net/wan/hdlc_fr.c
+++ b/drivers/net/wan/hdlc_fr.c
@@ -882,7 +882,7 @@  static int fr_rx(struct sk_buff *skb)
 	struct pvc_device *pvc;
 	struct net_device *dev;
 
-	if (skb->len <= 4 || fh->ea1 || data[2] != FR_UI)
+	if (skb->len < 4 || fh->ea1 || !fh->ea2 || data[2] != FR_UI)
 		goto rx_error;
 
 	dlci = q922_to_dlci(skb->data);