From: John Fastabend Date: Wed, 25 Apr 2018 22:08:53 +0000 (-0700) Subject: bpf: fix uninitialized variable in bpf tools X-Git-Tag: Ubuntu-4.15.0-37.40~208 X-Git-Url: https://git.proxmox.com/?a=commitdiff_plain;h=8a66565a6ed3edc758cf08f01882683ea5e72ec8;p=mirror_ubuntu-bionic-kernel.git bpf: fix uninitialized variable in bpf tools BugLink: http://bugs.launchpad.net/bugs/1794889 [ Upstream commit 815425567dea6c54494e85050631d6bdda907c5d ] Here the variable cont is used as the saved_pointer for a call to strtok_r(). It is safe to use the value uninitialized in this context however and the later reference is only ever used if the strtok_r is successful. But, 'gcc-5' at least doesn't have all this knowledge so initialize cont to NULL. Additionally, do the natural NULL check before accessing just for completness. The warning is the following: ./bpf/tools/bpf/bpf_dbg.c: In function ‘cmd_load’: ./bpf/tools/bpf/bpf_dbg.c:1077:13: warning: ‘cont’ may be used uninitialized in this function [-Wmaybe-uninitialized] } else if (matches(subcmd, "pcap") == 0) { Fixes: fd981e3c321a "filter: bpf_dbg: add minimal bpf debugger" Signed-off-by: John Fastabend Signed-off-by: Daniel Borkmann Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman Signed-off-by: Kamal Mostafa Signed-off-by: Stefan Bader --- diff --git a/tools/bpf/bpf_dbg.c b/tools/bpf/bpf_dbg.c index 4f254bcc4423..61b9aa5d6415 100644 --- a/tools/bpf/bpf_dbg.c +++ b/tools/bpf/bpf_dbg.c @@ -1063,7 +1063,7 @@ static int cmd_load_pcap(char *file) static int cmd_load(char *arg) { - char *subcmd, *cont, *tmp = strdup(arg); + char *subcmd, *cont = NULL, *tmp = strdup(arg); int ret = CMD_OK; subcmd = strtok_r(tmp, " ", &cont); @@ -1073,7 +1073,10 @@ static int cmd_load(char *arg) bpf_reset(); bpf_reset_breakpoints(); - ret = cmd_load_bpf(cont); + if (!cont) + ret = CMD_ERR; + else + ret = cmd_load_bpf(cont); } else if (matches(subcmd, "pcap") == 0) { ret = cmd_load_pcap(cont); } else {