From: Andrea Claudi Date: Tue, 26 May 2020 16:04:11 +0000 (+0200) Subject: bpf: Fixes a snprintf truncation warning X-Git-Tag: v5.7.0~3 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=354efaec3895f004382414f2df17e7d820e695f6;p=thirdparty%2Fiproute2.git bpf: Fixes a snprintf truncation warning gcc v9.3.1 reports: bpf.c: In function ‘bpf_get_work_dir’: bpf.c:784:49: warning: ‘snprintf’ output may be truncated before the last format character [-Wformat-truncation=] 784 | snprintf(bpf_wrk_dir, sizeof(bpf_wrk_dir), "%s/", mnt); | ^ bpf.c:784:2: note: ‘snprintf’ output between 2 and 4097 bytes into a destination of size 4096 784 | snprintf(bpf_wrk_dir, sizeof(bpf_wrk_dir), "%s/", mnt); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Fix this simply checking snprintf return code and properly handling the error. Fixes: e42256699cac ("bpf: make tc's bpf loader generic and move into lib") Signed-off-by: Andrea Claudi Signed-off-by: Stephen Hemminger --- diff --git a/lib/bpf.c b/lib/bpf.c index 23cb0d96a..c7d45077c 100644 --- a/lib/bpf.c +++ b/lib/bpf.c @@ -781,7 +781,11 @@ static const char *bpf_get_work_dir(enum bpf_prog_type type) } } - snprintf(bpf_wrk_dir, sizeof(bpf_wrk_dir), "%s/", mnt); + ret = snprintf(bpf_wrk_dir, sizeof(bpf_wrk_dir), "%s/", mnt); + if (ret < 0 || ret >= sizeof(bpf_wrk_dir)) { + mnt = NULL; + goto out; + } ret = bpf_gen_hierarchy(bpf_wrk_dir); if (ret) {