| Message ID | 20190418125827.57479-1-ldufour@linux.ibm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | mm: use mm.arg_lock in get_cmdline() | expand |
Michal has posted the same patch few days ago http://lkml.kernel.org/r/20190417120347.15397-1-mkoutny@suse.com On Thu 18-04-19 14:58:27, Laurent Dufour wrote: > The commit 88aa7cc688d4 ("mm: introduce arg_lock to protect arg_start|end > and env_start|end in mm_struct") introduce the spinlock arg_lock to protect > the arg_* and env_* field of the mm_struct structure. > > While reading the code, I found that this new spinlock was not used in > get_cmdline() to protect access to these fields. > > Fixing this even if there is no issue reported yet for this. > > Fixes: 88aa7cc688d4 ("mm: introduce arg_lock to protect arg_start|end and env_start|end in mm_struct") > Cc: Yang Shi <yang.shi@linux.alibaba.com> > Signed-off-by: Laurent Dufour <ldufour@linux.ibm.com> > --- > mm/util.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/mm/util.c b/mm/util.c > index 05a464929b3e..789760c3028b 100644 > --- a/mm/util.c > +++ b/mm/util.c > @@ -758,12 +758,12 @@ int get_cmdline(struct task_struct *task, char *buffer, int buflen) > if (!mm->arg_end) > goto out_mm; /* Shh! No looking before we're done */ > > - down_read(&mm->mmap_sem); > + spin_lock(&mm->arg_lock); > arg_start = mm->arg_start; > arg_end = mm->arg_end; > env_start = mm->env_start; > env_end = mm->env_end; > - up_read(&mm->mmap_sem); > + spin_unlock(&mm->arg_lock); > > len = arg_end - arg_start; > > -- > 2.21.0
Le 18/04/2019 à 15:03, Michal Hocko a écrit : > Michal has posted the same patch few days ago http://lkml.kernel.org/r/20190417120347.15397-1-mkoutny@suse.com Oups, sorry for the noise, I missed it. > On Thu 18-04-19 14:58:27, Laurent Dufour wrote: >> The commit 88aa7cc688d4 ("mm: introduce arg_lock to protect arg_start|end >> and env_start|end in mm_struct") introduce the spinlock arg_lock to protect >> the arg_* and env_* field of the mm_struct structure. >> >> While reading the code, I found that this new spinlock was not used in >> get_cmdline() to protect access to these fields. >> >> Fixing this even if there is no issue reported yet for this. >> >> Fixes: 88aa7cc688d4 ("mm: introduce arg_lock to protect arg_start|end and env_start|end in mm_struct") >> Cc: Yang Shi <yang.shi@linux.alibaba.com> >> Signed-off-by: Laurent Dufour <ldufour@linux.ibm.com> >> --- >> mm/util.c | 4 ++-- >> 1 file changed, 2 insertions(+), 2 deletions(-) >> >> diff --git a/mm/util.c b/mm/util.c >> index 05a464929b3e..789760c3028b 100644 >> --- a/mm/util.c >> +++ b/mm/util.c >> @@ -758,12 +758,12 @@ int get_cmdline(struct task_struct *task, char *buffer, int buflen) >> if (!mm->arg_end) >> goto out_mm; /* Shh! No looking before we're done */ >> >> - down_read(&mm->mmap_sem); >> + spin_lock(&mm->arg_lock); >> arg_start = mm->arg_start; >> arg_end = mm->arg_end; >> env_start = mm->env_start; >> env_end = mm->env_end; >> - up_read(&mm->mmap_sem); >> + spin_unlock(&mm->arg_lock); >> >> len = arg_end - arg_start; >> >> -- >> 2.21.0 >
On 4/18/19 6:05 AM, Laurent Dufour wrote: > Le 18/04/2019 à 15:03, Michal Hocko a écrit : >> Michal has posted the same patch few days ago >> http://lkml.kernel.org/r/20190417120347.15397-1-mkoutny@suse.com > > Oups, sorry for the noise, I missed it. Yes, Michal already posted a similar patch. Anyway, thanks for catching this. > >> On Thu 18-04-19 14:58:27, Laurent Dufour wrote: >>> The commit 88aa7cc688d4 ("mm: introduce arg_lock to protect >>> arg_start|end >>> and env_start|end in mm_struct") introduce the spinlock arg_lock to >>> protect >>> the arg_* and env_* field of the mm_struct structure. >>> >>> While reading the code, I found that this new spinlock was not used in >>> get_cmdline() to protect access to these fields. >>> >>> Fixing this even if there is no issue reported yet for this. >>> >>> Fixes: 88aa7cc688d4 ("mm: introduce arg_lock to protect >>> arg_start|end and env_start|end in mm_struct") >>> Cc: Yang Shi <yang.shi@linux.alibaba.com> >>> Signed-off-by: Laurent Dufour <ldufour@linux.ibm.com> >>> --- >>> mm/util.c | 4 ++-- >>> 1 file changed, 2 insertions(+), 2 deletions(-) >>> >>> diff --git a/mm/util.c b/mm/util.c >>> index 05a464929b3e..789760c3028b 100644 >>> --- a/mm/util.c >>> +++ b/mm/util.c >>> @@ -758,12 +758,12 @@ int get_cmdline(struct task_struct *task, char >>> *buffer, int buflen) >>> if (!mm->arg_end) >>> goto out_mm; /* Shh! No looking before we're done */ >>> - down_read(&mm->mmap_sem); >>> + spin_lock(&mm->arg_lock); >>> arg_start = mm->arg_start; >>> arg_end = mm->arg_end; >>> env_start = mm->env_start; >>> env_end = mm->env_end; >>> - up_read(&mm->mmap_sem); >>> + spin_unlock(&mm->arg_lock); >>> len = arg_end - arg_start; >>> -- >>> 2.21.0 >>
diff --git a/mm/util.c b/mm/util.c index 05a464929b3e..789760c3028b 100644 --- a/mm/util.c +++ b/mm/util.c @@ -758,12 +758,12 @@ int get_cmdline(struct task_struct *task, char *buffer, int buflen) if (!mm->arg_end) goto out_mm; /* Shh! No looking before we're done */ - down_read(&mm->mmap_sem); + spin_lock(&mm->arg_lock); arg_start = mm->arg_start; arg_end = mm->arg_end; env_start = mm->env_start; env_end = mm->env_end; - up_read(&mm->mmap_sem); + spin_unlock(&mm->arg_lock); len = arg_end - arg_start;
The commit 88aa7cc688d4 ("mm: introduce arg_lock to protect arg_start|end and env_start|end in mm_struct") introduce the spinlock arg_lock to protect the arg_* and env_* field of the mm_struct structure. While reading the code, I found that this new spinlock was not used in get_cmdline() to protect access to these fields. Fixing this even if there is no issue reported yet for this. Fixes: 88aa7cc688d4 ("mm: introduce arg_lock to protect arg_start|end and env_start|end in mm_struct") Cc: Yang Shi <yang.shi@linux.alibaba.com> Signed-off-by: Laurent Dufour <ldufour@linux.ibm.com> --- mm/util.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)