From: Jiri Olsa jolsa@redhat.com
[ Upstream commit aa52bcbe0e72fac36b1862db08b9c09c4caefae3 ]
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 Signed-off-by: Sasha Levin sashal@kernel.org --- tools/bpf/bpftool/jit_disasm.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-)
diff --git a/tools/bpf/bpftool/jit_disasm.c b/tools/bpf/bpftool/jit_disasm.c index 87439320ef70..73d7252729fa 100644 --- a/tools/bpf/bpftool/jit_disasm.c +++ b/tools/bpf/bpftool/jit_disasm.c @@ -10,6 +10,8 @@ * 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> @@ -51,11 +53,13 @@ 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] == ' ') @@ -68,11 +72,10 @@ 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; }