diff options
| author | Xu Kuohai <xukuohai@huawei.com> | 2022-10-18 10:55:38 -0400 |
|---|---|---|
| committer | Andrii Nakryiko <andrii@kernel.org> | 2022-10-21 14:28:14 -0700 |
| commit | d9740535b857650bd6211a67ac0c0d574cba1dce (patch) | |
| tree | 901bf64f17d5db7d104d9537327414e93700c42b /tools/lib | |
| parent | eb814cf1adea0ce24413c26c22e9f1a556a45d34 (diff) | |
| download | linux-d9740535b857650bd6211a67ac0c0d574cba1dce.tar.bz2 | |
libbpf: Avoid allocating reg_name with sscanf in parse_usdt_arg()
The reg_name in parse_usdt_arg() is used to hold register name, which
is short enough to be held in a 16-byte array, so we could define
reg_name as char reg_name[16] to avoid dynamically allocating reg_name
with sscanf.
Suggested-by: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Signed-off-by: Xu Kuohai <xukuohai@huawei.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/bpf/20221018145538.2046842-1-xukuohai@huaweicloud.com
Diffstat (limited to 'tools/lib')
| -rw-r--r-- | tools/lib/bpf/usdt.c | 16 |
1 files changed, 6 insertions, 10 deletions
diff --git a/tools/lib/bpf/usdt.c b/tools/lib/bpf/usdt.c index 49f3c3b7f609..28fa1b2283de 100644 --- a/tools/lib/bpf/usdt.c +++ b/tools/lib/bpf/usdt.c @@ -1225,26 +1225,24 @@ static int calc_pt_regs_off(const char *reg_name) static int parse_usdt_arg(const char *arg_str, int arg_num, struct usdt_arg_spec *arg) { - char *reg_name = NULL; + char reg_name[16]; int arg_sz, len, reg_off; long off; - if (sscanf(arg_str, " %d @ %ld ( %%%m[^)] ) %n", &arg_sz, &off, ®_name, &len) == 3) { + if (sscanf(arg_str, " %d @ %ld ( %%%15[^)] ) %n", &arg_sz, &off, reg_name, &len) == 3) { /* Memory dereference case, e.g., -4@-20(%rbp) */ arg->arg_type = USDT_ARG_REG_DEREF; arg->val_off = off; 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 @ %%%ms %n", &arg_sz, ®_name, &len) == 2) { + } else if (sscanf(arg_str, " %d @ %%%15s %n", &arg_sz, reg_name, &len) == 2) { /* Register read case, e.g., -4@%eax */ 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; @@ -1456,16 +1454,15 @@ static int calc_pt_regs_off(const char *reg_name) static int parse_usdt_arg(const char *arg_str, int arg_num, struct usdt_arg_spec *arg) { - char *reg_name = NULL; + char reg_name[16]; int arg_sz, len, reg_off; long off; - if (sscanf(arg_str, " %d @ %ld ( %m[a-z0-9] ) %n", &arg_sz, &off, ®_name, &len) == 3) { + if (sscanf(arg_str, " %d @ %ld ( %15[a-z0-9] ) %n", &arg_sz, &off, reg_name, &len) == 3) { /* Memory dereference case, e.g., -8@-88(s0) */ arg->arg_type = USDT_ARG_REG_DEREF; arg->val_off = off; reg_off = calc_pt_regs_off(reg_name); - free(reg_name); if (reg_off < 0) return reg_off; arg->reg_off = reg_off; @@ -1474,12 +1471,11 @@ static int parse_usdt_arg(const char *arg_str, int arg_num, struct usdt_arg_spec 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) { + } else if (sscanf(arg_str, " %d @ %15[a-z0-9] %n", &arg_sz, reg_name, &len) == 2) { /* Register read case, e.g., -8@a1 */ 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; |