On 10/11/2022 9:34 AM, Andrii Nakryiko wrote:
On Mon, Oct 10, 2022 at 7:08 AM Xu Kuohai xukuohai@huawei.com wrote:
In the arm64 version of parse_usdt_arg(), when sscanf returns 2, reg_name is allocated but not freed. Fix it.
Fixes: 0f8619929c57 ("libbpf: Usdt aarch64 arg parsing support") Signed-off-by: Xu Kuohai xukuohai@huawei.com
tools/lib/bpf/usdt.c | 59 +++++++++++++++++++++++++------------------- 1 file changed, 33 insertions(+), 26 deletions(-)
diff --git a/tools/lib/bpf/usdt.c b/tools/lib/bpf/usdt.c index e83b497c2245..f3b5be7415b5 100644 --- a/tools/lib/bpf/usdt.c +++ b/tools/lib/bpf/usdt.c @@ -1351,8 +1351,10 @@ static int parse_usdt_arg(const char *arg_str, int arg_num, struct usdt_arg_spec char *reg_name = NULL; int arg_sz, len, reg_off; long off;
int ret;
if (sscanf(arg_str, " %d @ \[ %m[a-z0-9], %ld ] %n", &arg_sz, ®_name, &off, &len) == 3) {
ret = sscanf(arg_str, " %d @ \[ %m[a-z0-9], %ld ] %n", &arg_sz, ®_name, &off, &len);if (ret == 3) { /* Memory dereference case, e.g., -4@[sp, 96] */ arg->arg_type = USDT_ARG_REG_DEREF; arg->val_off = off;@@ -1361,32 +1363,37 @@ static int parse_usdt_arg(const char *arg_str, int arg_num, struct usdt_arg_spec if (reg_off < 0) return reg_off; arg->reg_off = reg_off;
} else if (sscanf(arg_str, " %d @ \[ %m[a-z0-9] ] %n", &arg_sz, ®_name, &len) == 2) {/* Memory dereference case, e.g., -4@[sp] */arg->arg_type = USDT_ARG_REG_DEREF;arg->val_off = 0;reg_off = calc_pt_regs_off(reg_name);free(reg_name);if (reg_off < 0)return reg_off;arg->reg_off = reg_off;} else if (sscanf(arg_str, " %d @ %ld %n", &arg_sz, &off, &len) == 2) {/* Constant value case, e.g., 4@5 */arg->arg_type = USDT_ARG_CONST;arg->val_off = off;arg->reg_off = 0;} else if (sscanf(arg_str, " %d @ %m[a-z0-9] %n", &arg_sz, ®_name, &len) == 2) {/* Register read case, e.g., -8@x4 */arg->arg_type = USDT_ARG_REG;arg->val_off = 0;reg_off = calc_pt_regs_off(reg_name);free(reg_name);if (reg_off < 0)return reg_off;arg->reg_off = reg_off; } else {pr_warn("usdt: unrecognized arg #%d spec '%s'\n", arg_num, arg_str);return -EINVAL;
if (ret == 2)free(reg_name);if (sscanf(arg_str, " %d @ \[ %m[a-z0-9] ] %n", &arg_sz, ®_name, &len) == 2) {/* Memory dereference case, e.g., -4@[sp] */arg->arg_type = USDT_ARG_REG_DEREF;arg->val_off = 0;reg_off = calc_pt_regs_off(reg_name);free(reg_name);if (reg_off < 0)return reg_off;arg->reg_off = reg_off;} else if (sscanf(arg_str, " %d @ %ld %n", &arg_sz, &off, &len) == 2) {/* Constant value case, e.g., 4@5 */arg->arg_type = USDT_ARG_CONST;arg->val_off = off;arg->reg_off = 0;} else if (sscanf(arg_str, " %d @ %m[a-z0-9] %n", &arg_sz, ®_name, &len) == 2) {/* Register read case, e.g., -8@x4 */arg->arg_type = USDT_ARG_REG;arg->val_off = 0;reg_off = calc_pt_regs_off(reg_name);free(reg_name);if (reg_off < 0)return reg_off;arg->reg_off = reg_off;} else {pr_warn("usdt: unrecognized arg #%d spec '%s'\n", arg_num, arg_str);return -EINVAL;} }I think all this is more complicated than it has to be. How big can register names be? Few characters? Let's get rid of %m[a-z0-9] and instead use fixed-max-length strings, e.g., %5s. And read register names into such local char buffers. It will simplify everything tremendously. Let's use 16-byte buffers and use %15s to match it? Would that be enough?
The valid register names accepted by calc_pt_regs_off() are x0~x31 and sp, so 16-byte buffer is enough. Since %15s matches all non-space characters, will use %15[a-z0-9] to match it.
arg->arg_signed = arg_sz < 0;-- 2.30.2
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