From 7c87c7fed18d1162e045c8331cb68fa440bc5728 Mon Sep 17 00:00:00 2001 From: Phil Sutter Date: Tue, 29 Aug 2017 17:09:45 +0200 Subject: [PATCH] lib/bpf: Fix bytecode-file parsing The signedness of char type is implementation dependent, and there are architectures on which it is unsigned by default. In that case, the check whether fgetc() returned EOF failed because the return value was assigned an (unsigned) char variable prior to comparison with EOF (which is defined to -1). Fix this by using int as type for 'c' variable, which also matches the declaration of fgetc(). While being at it, fix the parser logic to correctly handle multiple empty lines and consecutive whitespace and tab characters to further improve the parser's robustness. Note that this will still detect double separator characters, so doesn't soften up the parser too much. Fixes: 3da3ebfca85b8 ("bpf: Make bytecode-file reading a little more robust") Cc: Daniel Borkmann Signed-off-by: Phil Sutter Acked-by: Daniel Borkmann --- lib/bpf.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/lib/bpf.c b/lib/bpf.c index c180934a..5fd4928c 100644 --- a/lib/bpf.c +++ b/lib/bpf.c @@ -208,8 +208,9 @@ static int bpf_parse_string(char *arg, bool from_file, __u16 *bpf_len, if (from_file) { size_t tmp_len, op_len = sizeof("65535 255 255 4294967295,"); - char *tmp_string, *pos, c, c_prev = ' '; + char *tmp_string, *pos, c_prev = ' '; FILE *fp; + int c; tmp_len = sizeof("4096,") + BPF_MAXINSNS * op_len; tmp_string = pos = calloc(1, tmp_len); @@ -228,18 +229,20 @@ static int bpf_parse_string(char *arg, bool from_file, __u16 *bpf_len, case '\n': if (c_prev != ',') *(pos++) = ','; + c_prev = ','; break; case ' ': case '\t': if (c_prev != ' ') *(pos++) = c; + c_prev = ' '; break; default: *(pos++) = c; + c_prev = c; } if (pos - tmp_string == tmp_len) break; - c_prev = c; } if (!feof(fp)) {