Messages in this thread | | | Date | Fri, 14 Oct 2022 09:53:23 +0800 | Subject | Re: [PATCH bpf-next v4 2/6] libbpf: Fix memory leak in parse_usdt_arg() | From | Xu Kuohai <> |
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On 10/13/2022 11:47 PM, Andrii Nakryiko wrote: > On Tue, Oct 11, 2022 at 4:43 AM Xu Kuohai <xukuohai@huaweicloud.com> wrote: >> >> From: Xu Kuohai <xukuohai@huawei.com> >> >> 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 | 11 ++++------- >> 1 file changed, 4 insertions(+), 7 deletions(-) >> >> diff --git a/tools/lib/bpf/usdt.c b/tools/lib/bpf/usdt.c >> index e83b497c2245..49f3c3b7f609 100644 >> --- a/tools/lib/bpf/usdt.c >> +++ b/tools/lib/bpf/usdt.c >> @@ -1348,25 +1348,23 @@ 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 @ \[ %m[a-z0-9], %ld ] %n", &arg_sz, ®_name, &off, &len) == 3) { >> + if (sscanf(arg_str, " %d @ \[ %15[a-z0-9], %ld ] %n", &arg_sz, reg_name, &off, &len) == 3) { > > It would be nice to do the same change for other architectures where > it makes sense and avoid having to deal with unnecessary memory > allocations. Please send follow up patches with similar changes for > other implementations of parse_usdt_arg. Thanks. >
ok, will do
> >> /* Memory dereference case, e.g., -4@[sp, 96] */ >> 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 @ \[ %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) { >> /* 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; >> @@ -1375,12 +1373,11 @@ 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@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; >> -- >> 2.30.2 >> > .
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