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Message-ID: <YeWOd2G69LyR3PVZ@dhcp22.suse.cz>
Date: Mon, 17 Jan 2022 16:42:47 +0100
From: Michal Hocko <mhocko@...e.com>
To: Christophe JAILLET <christophe.jaillet@...adoo.fr>
Cc: Andy Shevchenko <andy@...nel.org>,
Stephen Rothwell <sfr@...b.auug.org.au>,
Andrew Morton <akpm@...ux-foundation.org>,
Mel Gorman <mgorman@...e.de>, Vlastimil Babka <vbabka@...e.cz>,
linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: Re: [PATCH] lib/string_helpers: Use the given gfp flag when
allocating memory
On Mon 17-01-22 10:51:59, Michal Hocko wrote:
> On Sun 16-01-22 13:49:22, Christophe JAILLET wrote:
> > kstrdup_quotable_cmdline() is given a gfp flag that is passed and used for
> > memory allocation in kstrdup_quotable() just a few lines below.
> >
> > It looks reasonable to use this gfp value for the buffer allocated and
> > freed in kstrdup_quotable_cmdline() as well.
> >
> > Fixes: 0ee931c4e31a ("mm: treewide: remove GFP_TEMPORARY allocation flag")
>
> I do not think this commit is changing much here. It just replaces
> GFP_TEMPORARY with GFP_KERNEL so the code has ignored the gfp mask even
> before that change.
>
> All existing callers of kstrdup_quotable_cmdline use GFP_KERNEL so would
> it make more sense to simply drop the gfp argument altogether and use
> GFP_KERNEL internally?
>
> Normally it is better to have a full control of the allocation mask but
> if we have any non-GFP_KERNEL caller then I would rather have the
> argument added and the function checked whether all internal paths are
> gfp mask aware.
In other words something like this:
diff --git a/drivers/gpu/drm/msm/msm_gpu.c b/drivers/gpu/drm/msm/msm_gpu.c
index 2c46cd968ac4..44fde4b537f1 100644
--- a/drivers/gpu/drm/msm/msm_gpu.c
+++ b/drivers/gpu/drm/msm/msm_gpu.c
@@ -376,7 +376,7 @@ static void recover_worker(struct kthread_work *work)
task = get_pid_task(submit->pid, PIDTYPE_PID);
if (task) {
comm = kstrdup(task->comm, GFP_KERNEL);
- cmd = kstrdup_quotable_cmdline(task, GFP_KERNEL);
+ cmd = kstrdup_quotable_cmdline(task);
put_task_struct(task);
}
@@ -467,7 +467,7 @@ static void fault_worker(struct kthread_work *work)
task = get_pid_task(submit->pid, PIDTYPE_PID);
if (task) {
comm = kstrdup(task->comm, GFP_KERNEL);
- cmd = kstrdup_quotable_cmdline(task, GFP_KERNEL);
+ cmd = kstrdup_quotable_cmdline(task);
put_task_struct(task);
}
diff --git a/include/linux/string_helpers.h b/include/linux/string_helpers.h
index 4ba39e1403b2..7a67eee8bd0f 100644
--- a/include/linux/string_helpers.h
+++ b/include/linux/string_helpers.h
@@ -97,8 +97,8 @@ static inline void string_lower(char *dst, const char *src)
}
char *kstrdup_quotable(const char *src, gfp_t gfp);
-char *kstrdup_quotable_cmdline(struct task_struct *task, gfp_t gfp);
-char *kstrdup_quotable_file(struct file *file, gfp_t gfp);
+char *kstrdup_quotable_cmdline(struct task_struct *task);
+char *kstrdup_quotable_file(struct file *file);
void kfree_strarray(char **array, size_t n);
diff --git a/lib/string_helpers.c b/lib/string_helpers.c
index d5d008f5b1d9..267e142c7e13 100644
--- a/lib/string_helpers.c
+++ b/lib/string_helpers.c
@@ -618,12 +618,13 @@ EXPORT_SYMBOL_GPL(kstrdup_quotable);
* command line, with inter-argument NULLs replaced with spaces,
* and other special characters escaped.
*/
-char *kstrdup_quotable_cmdline(struct task_struct *task, gfp_t gfp)
+char *kstrdup_quotable_cmdline(struct task_struct *task)
{
+ gfp_t gfp = GFP_KERNEL;
char *buffer, *quoted;
int i, res;
- buffer = kmalloc(PAGE_SIZE, GFP_KERNEL);
+ buffer = kmalloc(PAGE_SIZE, gfp);
if (!buffer)
return NULL;
@@ -651,15 +652,16 @@ EXPORT_SYMBOL_GPL(kstrdup_quotable_cmdline);
* with special characters escaped, able to be safely logged. If
* there is an error, the leading character will be "<".
*/
-char *kstrdup_quotable_file(struct file *file, gfp_t gfp)
+char *kstrdup_quotable_file(struct file *file)
{
+ gfp_t gfp = GFP_KERNEL;
char *temp, *pathname;
if (!file)
return kstrdup("<unknown>", gfp);
/* We add 11 spaces for ' (deleted)' to be appended */
- temp = kmalloc(PATH_MAX + 11, GFP_KERNEL);
+ temp = kmalloc(PATH_MAX + 11, gfp);
if (!temp)
return kstrdup("<no_memory>", gfp);
diff --git a/security/loadpin/loadpin.c b/security/loadpin/loadpin.c
index b12f7d986b1e..79322ba89913 100644
--- a/security/loadpin/loadpin.c
+++ b/security/loadpin/loadpin.c
@@ -23,8 +23,8 @@ static void report_load(const char *origin, struct file *file, char *operation)
{
char *cmdline, *pathname;
- pathname = kstrdup_quotable_file(file, GFP_KERNEL);
- cmdline = kstrdup_quotable_cmdline(current, GFP_KERNEL);
+ pathname = kstrdup_quotable_file(file);
+ cmdline = kstrdup_quotable_cmdline(current);
pr_notice("%s %s obj=%s%s%s pid=%d cmdline=%s%s%s\n",
origin, operation,
diff --git a/security/yama/yama_lsm.c b/security/yama/yama_lsm.c
index 06e226166aab..c87a41304b6c 100644
--- a/security/yama/yama_lsm.c
+++ b/security/yama/yama_lsm.c
@@ -54,8 +54,8 @@ static void __report_access(struct callback_head *work)
container_of(work, struct access_report_info, work);
char *target_cmd, *agent_cmd;
- target_cmd = kstrdup_quotable_cmdline(info->target, GFP_KERNEL);
- agent_cmd = kstrdup_quotable_cmdline(info->agent, GFP_KERNEL);
+ target_cmd = kstrdup_quotable_cmdline(info->target);
+ agent_cmd = kstrdup_quotable_cmdline(info->agent);
pr_notice_ratelimited(
"ptrace %s of \"%s\"[%d] was attempted by \"%s\"[%d]\n",
--
Michal Hocko
SUSE Labs
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