print-bgp: account for TLV header bytes in L2VPN tlen tracking#1444
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print-bgp: account for TLV header bytes in L2VPN tlen tracking#1444TristanInSec wants to merge 1 commit into
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print_labeled_vpn_l2() reads a 3-byte TLV header (1-byte type + 2-byte length) per iteration and advances pptr by 3 bytes, but does not subtract the header bytes from tlen. Only the data portion (ttlv_len) is subtracted via tlen -= ttlv_len (default case) or tlen-- per byte (case 1). After N TLVs, tlen is 3*N bytes too high, so the while (tlen != 0) loop continues past the L2VPN attribute boundary, interpreting adjacent BGP path attribute data as TLV structures. Fix by subtracting the 3-byte header from tlen immediately after reading it.
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print_labeled_vpn_l2() reads a 3-byte TLV header (1-byte type +
2-byte length) per iteration and advances pptr by 3, but does not
subtract the header bytes from tlen. Only the data portion is
subtracted via tlen -= ttlv_len (default case) or tlen-- per byte
(case 1).
After N TLVs, tlen is 3*N bytes too high, causing the
while (tlen != 0) loop to continue past the L2VPN attribute
boundary and interpret adjacent BGP path attribute data as TLV
structures.
Fix by subtracting the 3-byte TLV header from tlen immediately
after reading it.
Found by manual audit of commit 9ec6904.