net/icmp: Fix devif_loopback dead loop when unrecognized ICMP packet #17890
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…received When an unrecognized ICMP (type=3, code=2) packet is received, the ICMP flow does not set dev->d_len to 0, causing a devif_loopback dead loop. Therefore, in ICMP input processing, when an ICMP_DEST_UNREACHABLE message is received, if it is not ICMP_FRAG_NEEDED code, jump to typeerr for error handling. Signed-off-by: daichuan <[email protected]>
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xiaoxiang781216
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Jan 14, 2026
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Summary
When an unrecognized ICMP (type=3, code=2) packet is received, the ICMP flow does not set dev->d_len to 0, causing a devif_loopback dead loop.
Therefore, in ICMP input processing, when an ICMP_DEST_UNREACHABLE message is received, if it is not ICMP_FRAG_NEEDED code, jump to typeerr for proper error handling.
Impact
Fixes a endless loop in devif_loopback when handling unrecognized ICMP packets (specifically type 3, code 2). This improves system stability when facing unexpected network traffic.
Testing
Verified with ICMP packets (type=3, code=2). The system no longer enters a dead loop and correctly handles the error.