tools: bpftool: fix crash with un-owned prog arrays

Prog arrays don't have 'owner_prog_type' and 'owner_jited'
fields in their fdinfo when they are created.  Those fields
are set and reported when first program is checked for
compatibility by bpf_prog_array_compatible().

This means that bpftool cannot expect the fields to always
be there.  Currently trying to show maps on a system with
an un-owned prog array leads to a crash:

$ bpftool map show
389: prog_array  name tail_call_map  flags 0x0
Error: key 'owner_prog_type' not found in fdinfo
Error: key 'owner_jited' not found in fdinfo
       key 4B  value 4B  max_entries 4  memlock 4096B
       Segmentation fault (core dumped)

We pass a NULL pointer to atoi().

Remove the assumption that fdinfo keys are always present.
Add missing validations and remove the p_err() calls which
may lead to broken JSON output as caller will not propagate
the failure.

Fixes: 99a44bef5870 ("tools: bpftool: add owner_prog_type and owner_jited to bpftool output")
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

1 files changed, 1 insertions, 5 deletions

diff --git a/tools/bpf/bpftool/common.c b/tools/bpf/bpftool/common.c
index 897483457bf0..f7261fad45c1 100644
--- a/tools/bpf/bpftool/common.c
+++ b/tools/bpf/bpftool/common.c
@@ -297,10 +297,8 @@ char *get_fdinfo(int fd, const char *key)
 	snprintf(path, sizeof(path), "/proc/self/fdinfo/%d", fd);
 
 	fdi = fopen(path, "r");
-	if (!fdi) {
-		p_err("can't open fdinfo: %s", strerror(errno));
+	if (!fdi)
 		return NULL;
-	}
 
 	while ((n = getline(&line, &line_n, fdi)) > 0) {
 		char *value;
@@ -313,7 +311,6 @@ char *get_fdinfo(int fd, const char *key)
 
 		value = strchr(line, '\t');
 		if (!value || !value[1]) {
-			p_err("malformed fdinfo!?");
 			free(line);
 			return NULL;
 		}
@@ -326,7 +323,6 @@ char *get_fdinfo(int fd, const char *key)
 		return line;
 	}
 
-	p_err("key '%s' not found in fdinfo", key);
 	free(line);
 	fclose(fdi);
 	return NULL;