Issue #1816 has been updated by tuxillo. Description updated Status changed from New to Closed % Done changed from 0 to 100
Already fixed some 12 years ago in this commit: https://github.com/the-tcpdump-group/libpcap/commit/b26d8d2aa849c8021cdfa872901e82fb469460ef We have a version that has the fix. ---------------------------------------- Bug #1816: p->cc can go negative in libpcap http://bugs.dragonflybsd.org/issues/1816#change-14273 * Author: guy * Status: Closed * Priority: Normal * Assignee: sjg * Target version: 6.4 ---------------------------------------- In pcap_read_bpf(), ep is set based on the return value of read(), but read() from a BPF device doesn't necessarily return a value that's a multiple of the alignment value for BPF_WORDALIGN(). However, whenever we increment bp, we round up the increment value by a value rounded up by BPF_WORDALIGN(), so we could increment bp past ep after processing the last packet in the buffer. This can be reproduced by running a program that opens a capture device with a timeout of 0, in a loop, calls pcap_dispatch() with a cnt argument of 1, and reports when it returns a value of 0. The timeout of 0 means that the read() that libpcap does shouldn't return until there's packet data, so a timeout won't cause pcap_dispatch() to return 0. Do a large amount of network data transfer, to fill up the BPF bucket; notice that, on occasion, the program will report that pcap_dispatch() returns 0. See the attached patch, which also fixes a case where, if you break out of the packet read loop due to a pcap_breakloop() call, p->bp isn't advanced and p->cc isn't reduced. ---Files-------------------------------- patch.txt (1.18 KB) -- You have received this notification because you have either subscribed to it, or are involved in it. To change your notification preferences, please click here: http://bugs.dragonflybsd.org/my/account
