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authorJiri Olsa <jolsa@redhat.com>2019-07-05 14:10:31 +0200
committerDaniel Borkmann <daniel@iogearbox.net>2019-07-05 23:50:38 +0200
commitaa52bcbe0e72fac36b1862db08b9c09c4caefae3 (patch)
tree294e313612adbc94ce8a4ce936b74ac30a7d22fb /tools/bpf
parentba95c7452439756d4f6dceb5a188b7c31dbbe5b6 (diff)
tools: bpftool: Fix json dump crash on powerpc
Michael reported crash with by bpf program in json mode on powerpc: # bpftool prog -p dump jited id 14 [{ "name": "0xd00000000a9aa760", "insns": [{ "pc": "0x0", "operation": "nop", "operands": [null ] },{ "pc": "0x4", "operation": "nop", "operands": [null ] },{ "pc": "0x8", "operation": "mflr", Segmentation fault (core dumped) The code is assuming char pointers in format, which is not always true at least for powerpc. Fixing this by dumping the whole string into buffer based on its format. Please note that libopcodes code does not check return values from fprintf callback, but as per Jakub suggestion returning -1 on allocation failure so we do the best effort to propagate the error. Fixes: 107f041212c1 ("tools: bpftool: add JSON output for `bpftool prog dump jited *` command") Reported-by: Michael Petlan <mpetlan@redhat.com> Signed-off-by: Jiri Olsa <jolsa@kernel.org> Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com> Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Diffstat (limited to 'tools/bpf')
-rw-r--r--tools/bpf/bpftool/jit_disasm.c11
1 files changed, 7 insertions, 4 deletions
diff --git a/tools/bpf/bpftool/jit_disasm.c b/tools/bpf/bpftool/jit_disasm.c
index 3ef3093560ba..bfed711258ce 100644
--- a/tools/bpf/bpftool/jit_disasm.c
+++ b/tools/bpf/bpftool/jit_disasm.c
@@ -11,6 +11,8 @@
* Licensed under the GNU General Public License, version 2.0 (GPLv2)
*/
+#define _GNU_SOURCE
+#include <stdio.h>
#include <stdarg.h>
#include <stdint.h>
#include <stdio.h>
@@ -44,11 +46,13 @@ static int fprintf_json(void *out, const char *fmt, ...)
char *s;
va_start(ap, fmt);
+ if (vasprintf(&s, fmt, ap) < 0)
+ return -1;
+ va_end(ap);
+
if (!oper_count) {
int i;
- s = va_arg(ap, char *);
-
/* Strip trailing spaces */
i = strlen(s) - 1;
while (s[i] == ' ')
@@ -61,11 +65,10 @@ static int fprintf_json(void *out, const char *fmt, ...)
} else if (!strcmp(fmt, ",")) {
/* Skip */
} else {
- s = va_arg(ap, char *);
jsonw_string(json_wtr, s);
oper_count++;
}
- va_end(ap);
+ free(s);
return 0;
}