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Date: Mon, 7 Mar 2022 19:07:10 +0100
From: Andrea Claudi <aclaudi@...hat.com>
To: Leon Romanovsky <leon@...nel.org>
Cc: netdev@...r.kernel.org, stephen@...workplumber.org,
dsahern@...il.com, markzhang@...dia.com
Subject: Re: [PATCH iproute2 v2 1/2] lib/fs: fix memory leak in
get_task_name()
Hi Leon,
Thanks for your review.
On Thu, Mar 03, 2022 at 08:56:57PM +0200, Leon Romanovsky wrote:
> On Wed, Mar 02, 2022 at 01:28:47PM +0100, Andrea Claudi wrote:
> > asprintf() allocates memory which is not freed on the error path of
> > get_task_name(), thus potentially leading to memory leaks.
>
> Not really, memory is released when the application exits, which is the
> case here.
>
That's certainly true. However this is still a leak in the time frame
between get_task_name function call and the application exit. For
example:
$ ip -d -b - << EOF
tuntap show
monitor
EOF
calls get_task_name one or more time (once for each tun interface), and
leaks memory indefinitely, if ip is not interrupted in some way.
Of course this is a corner case, and the leaks should anyway be small.
However I cannot see this as a good reason not to fix it.
> >
> > Rework get_task_name() and avoid asprintf() usage and memory allocation,
> > returning the task string to the caller using an additional char*
> > parameter.
> >
> > Fixes: 81bfd01a4c9e ("lib: move get_task_name() from rdma")
>
> As I was told before, in netdev Fixes means that it is a bug that
> affects users. This is not the case here.
Thanks for letting me know. I usually rely a lot on Fixes: as iproute2
package maintainer, but I'll change my habits if this is the common
understanding. Stephen, David, WDYT?
>
> > Signed-off-by: Andrea Claudi <aclaudi@...hat.com>
> > ---
> > include/utils.h | 2 +-
> > ip/iptuntap.c | 17 ++++++++++-------
> > lib/fs.c | 20 ++++++++++----------
> > rdma/res-cmid.c | 8 +++++---
> > rdma/res-cq.c | 8 +++++---
> > rdma/res-ctx.c | 7 ++++---
> > rdma/res-mr.c | 7 ++++---
> > rdma/res-pd.c | 8 +++++---
> > rdma/res-qp.c | 7 ++++---
> > rdma/res-srq.c | 7 ++++---
> > rdma/stat.c | 5 ++++-
> > 11 files changed, 56 insertions(+), 40 deletions(-)
>
> Honestly, I don't see any need in both patches.
>
> Thanks
>
> >
> > diff --git a/include/utils.h b/include/utils.h
> > index b6c468e9..81294488 100644
> > --- a/include/utils.h
> > +++ b/include/utils.h
> > @@ -307,7 +307,7 @@ char *find_cgroup2_mount(bool do_mount);
> > __u64 get_cgroup2_id(const char *path);
> > char *get_cgroup2_path(__u64 id, bool full);
> > int get_command_name(const char *pid, char *comm, size_t len);
> > -char *get_task_name(pid_t pid);
> > +int get_task_name(pid_t pid, char *name);
> >
> > int get_rtnl_link_stats_rta(struct rtnl_link_stats64 *stats64,
> > struct rtattr *tb[]);
> > diff --git a/ip/iptuntap.c b/ip/iptuntap.c
> > index 385d2bd8..2ae6b1a1 100644
> > --- a/ip/iptuntap.c
> > +++ b/ip/iptuntap.c
> > @@ -321,14 +321,17 @@ static void show_processes(const char *name)
> > } else if (err == 2 &&
> > !strcmp("iff", key) &&
> > !strcmp(name, value)) {
> > - char *pname = get_task_name(pid);
> > -
> > - print_string(PRINT_ANY, "name",
> > - "%s", pname ? : "<NULL>");
> > + SPRINT_BUF(pname);
> > +
> > + if (get_task_name(pid, pname)) {
> > + print_string(PRINT_ANY, "name",
> > + "%s", "<NULL>");
> > + } else {
> > + print_string(PRINT_ANY, "name",
> > + "%s", pname);
> > + }
> >
> > - print_uint(PRINT_ANY, "pid",
> > - "(%d)", pid);
> > - free(pname);
> > + print_uint(PRINT_ANY, "pid", "(%d)", pid);
> > }
> >
> > free(key);
> > diff --git a/lib/fs.c b/lib/fs.c
> > index f6f5f8a0..03df0f6a 100644
> > --- a/lib/fs.c
> > +++ b/lib/fs.c
> > @@ -342,25 +342,25 @@ int get_command_name(const char *pid, char *comm, size_t len)
> > return 0;
> > }
> >
> > -char *get_task_name(pid_t pid)
> > +int get_task_name(pid_t pid, char *name)
> > {
> > - char *comm;
> > + char path[PATH_MAX];
> > FILE *f;
> >
> > if (!pid)
> > - return NULL;
> > + return -1;
> >
> > - if (asprintf(&comm, "/proc/%d/comm", pid) < 0)
> > - return NULL;
> > + if (snprintf(path, sizeof(path), "/proc/%d/comm", pid) >= sizeof(path))
> > + return -1;
> >
> > - f = fopen(comm, "r");
> > + f = fopen(path, "r");
> > if (!f)
> > - return NULL;
> > + return -1;
> >
> > - if (fscanf(f, "%ms\n", &comm) != 1)
> > - comm = NULL;
> > + if (fscanf(f, "%s\n", name) != 1)
> > + return -1;
> >
> > fclose(f);
> >
> > - return comm;
> > + return 0;
> > }
> > diff --git a/rdma/res-cmid.c b/rdma/res-cmid.c
> > index bfaa47b5..3475349d 100644
> > --- a/rdma/res-cmid.c
> > +++ b/rdma/res-cmid.c
> > @@ -159,8 +159,11 @@ static int res_cm_id_line(struct rd *rd, const char *name, int idx,
> > goto out;
> >
> > if (nla_line[RDMA_NLDEV_ATTR_RES_PID]) {
> > + SPRINT_BUF(b);
> > +
> > pid = mnl_attr_get_u32(nla_line[RDMA_NLDEV_ATTR_RES_PID]);
> > - comm = get_task_name(pid);
> > + if (!get_task_name(pid, b))
> > + comm = b;
> > }
> >
> > if (rd_is_filtered_attr(rd, "pid", pid,
> > @@ -199,8 +202,7 @@ static int res_cm_id_line(struct rd *rd, const char *name, int idx,
> > print_driver_table(rd, nla_line[RDMA_NLDEV_ATTR_DRIVER]);
> > newline(rd);
> >
> > -out: if (nla_line[RDMA_NLDEV_ATTR_RES_PID])
> > - free(comm);
> > +out:
> > return MNL_CB_OK;
> > }
> >
> > diff --git a/rdma/res-cq.c b/rdma/res-cq.c
> > index 9e7c4f51..5ed455ea 100644
> > --- a/rdma/res-cq.c
> > +++ b/rdma/res-cq.c
> > @@ -84,8 +84,11 @@ static int res_cq_line(struct rd *rd, const char *name, int idx,
> > goto out;
> >
> > if (nla_line[RDMA_NLDEV_ATTR_RES_PID]) {
> > + SPRINT_BUF(b);
> > +
> > pid = mnl_attr_get_u32(nla_line[RDMA_NLDEV_ATTR_RES_PID]);
> > - comm = get_task_name(pid);
> > + if (!get_task_name(pid, b))
> > + comm = b;
> > }
> >
> > if (rd_is_filtered_attr(rd, "pid", pid,
> > @@ -123,8 +126,7 @@ static int res_cq_line(struct rd *rd, const char *name, int idx,
> > print_driver_table(rd, nla_line[RDMA_NLDEV_ATTR_DRIVER]);
> > newline(rd);
> >
> > -out: if (nla_line[RDMA_NLDEV_ATTR_RES_PID])
> > - free(comm);
> > +out:
> > return MNL_CB_OK;
> > }
> >
> > diff --git a/rdma/res-ctx.c b/rdma/res-ctx.c
> > index 30afe97a..fbd52dd5 100644
> > --- a/rdma/res-ctx.c
> > +++ b/rdma/res-ctx.c
> > @@ -18,8 +18,11 @@ static int res_ctx_line(struct rd *rd, const char *name, int idx,
> > return MNL_CB_ERROR;
> >
> > if (nla_line[RDMA_NLDEV_ATTR_RES_PID]) {
> > + SPRINT_BUF(b);
> > +
> > pid = mnl_attr_get_u32(nla_line[RDMA_NLDEV_ATTR_RES_PID]);
> > - comm = get_task_name(pid);
> > + if (!get_task_name(pid, b))
> > + comm = b;
> > }
> >
> > if (rd_is_filtered_attr(rd, "pid", pid,
> > @@ -48,8 +51,6 @@ static int res_ctx_line(struct rd *rd, const char *name, int idx,
> > newline(rd);
> >
> > out:
> > - if (nla_line[RDMA_NLDEV_ATTR_RES_PID])
> > - free(comm);
> > return MNL_CB_OK;
> > }
> >
> > diff --git a/rdma/res-mr.c b/rdma/res-mr.c
> > index 1bf73f3a..6a59d9e4 100644
> > --- a/rdma/res-mr.c
> > +++ b/rdma/res-mr.c
> > @@ -47,8 +47,11 @@ static int res_mr_line(struct rd *rd, const char *name, int idx,
> > goto out;
> >
> > if (nla_line[RDMA_NLDEV_ATTR_RES_PID]) {
> > + SPRINT_BUF(b);
> > +
> > pid = mnl_attr_get_u32(nla_line[RDMA_NLDEV_ATTR_RES_PID]);
> > - comm = get_task_name(pid);
> > + if (!get_task_name(pid, b))
> > + comm = b;
> > }
> >
> > if (rd_is_filtered_attr(rd, "pid", pid,
> > @@ -87,8 +90,6 @@ static int res_mr_line(struct rd *rd, const char *name, int idx,
> > newline(rd);
> >
> > out:
> > - if (nla_line[RDMA_NLDEV_ATTR_RES_PID])
> > - free(comm);
> > return MNL_CB_OK;
> > }
> >
> > diff --git a/rdma/res-pd.c b/rdma/res-pd.c
> > index df538010..a51bb634 100644
> > --- a/rdma/res-pd.c
> > +++ b/rdma/res-pd.c
> > @@ -34,8 +34,11 @@ static int res_pd_line(struct rd *rd, const char *name, int idx,
> > nla_line[RDMA_NLDEV_ATTR_RES_UNSAFE_GLOBAL_RKEY]);
> >
> > if (nla_line[RDMA_NLDEV_ATTR_RES_PID]) {
> > + SPRINT_BUF(b);
> > +
> > pid = mnl_attr_get_u32(nla_line[RDMA_NLDEV_ATTR_RES_PID]);
> > - comm = get_task_name(pid);
> > + if (!get_task_name(pid, b))
> > + comm = b;
> > }
> >
> > if (rd_is_filtered_attr(rd, "pid", pid,
> > @@ -76,8 +79,7 @@ static int res_pd_line(struct rd *rd, const char *name, int idx,
> > print_driver_table(rd, nla_line[RDMA_NLDEV_ATTR_DRIVER]);
> > newline(rd);
> >
> > -out: if (nla_line[RDMA_NLDEV_ATTR_RES_PID])
> > - free(comm);
> > +out:
> > return MNL_CB_OK;
> > }
> >
> > diff --git a/rdma/res-qp.c b/rdma/res-qp.c
> > index a38be399..575e0529 100644
> > --- a/rdma/res-qp.c
> > +++ b/rdma/res-qp.c
> > @@ -146,8 +146,11 @@ static int res_qp_line(struct rd *rd, const char *name, int idx,
> > goto out;
> >
> > if (nla_line[RDMA_NLDEV_ATTR_RES_PID]) {
> > + SPRINT_BUF(b);
> > +
> > pid = mnl_attr_get_u32(nla_line[RDMA_NLDEV_ATTR_RES_PID]);
> > - comm = get_task_name(pid);
> > + if (!get_task_name(pid, b))
> > + comm = b;
> > }
> >
> > if (rd_is_filtered_attr(rd, "pid", pid,
> > @@ -179,8 +182,6 @@ static int res_qp_line(struct rd *rd, const char *name, int idx,
> > print_driver_table(rd, nla_line[RDMA_NLDEV_ATTR_DRIVER]);
> > newline(rd);
> > out:
> > - if (nla_line[RDMA_NLDEV_ATTR_RES_PID])
> > - free(comm);
> > return MNL_CB_OK;
> > }
> >
> > diff --git a/rdma/res-srq.c b/rdma/res-srq.c
> > index 3038c352..945109fc 100644
> > --- a/rdma/res-srq.c
> > +++ b/rdma/res-srq.c
> > @@ -174,8 +174,11 @@ static int res_srq_line(struct rd *rd, const char *name, int idx,
> > return MNL_CB_ERROR;
> >
> > if (nla_line[RDMA_NLDEV_ATTR_RES_PID]) {
> > + SPRINT_BUF(b);
> > +
> > pid = mnl_attr_get_u32(nla_line[RDMA_NLDEV_ATTR_RES_PID]);
> > - comm = get_task_name(pid);
> > + if (!get_task_name(pid, b))
> > + comm = b;
> > }
> > if (rd_is_filtered_attr(rd, "pid", pid,
> > nla_line[RDMA_NLDEV_ATTR_RES_PID]))
> > @@ -228,8 +231,6 @@ static int res_srq_line(struct rd *rd, const char *name, int idx,
> > newline(rd);
> >
> > out:
> > - if (nla_line[RDMA_NLDEV_ATTR_RES_PID])
> > - free(comm);
> > return MNL_CB_OK;
> > }
> >
> > diff --git a/rdma/stat.c b/rdma/stat.c
> > index adfcd34a..a63b70a4 100644
> > --- a/rdma/stat.c
> > +++ b/rdma/stat.c
> > @@ -248,8 +248,11 @@ static int res_counter_line(struct rd *rd, const char *name, int index,
> > return MNL_CB_OK;
> >
> > if (nla_line[RDMA_NLDEV_ATTR_RES_PID]) {
> > + SPRINT_BUF(b);
> > +
> > pid = mnl_attr_get_u32(nla_line[RDMA_NLDEV_ATTR_RES_PID]);
> > - comm = get_task_name(pid);
> > + if (!get_task_name(pid, b))
> > + comm = b;
> > }
> > if (rd_is_filtered_attr(rd, "pid", pid,
> > nla_line[RDMA_NLDEV_ATTR_RES_PID]))
> > --
> > 2.35.1
> >
>
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