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| author | Vasily Averin <vvs@virtuozzo.com> | 2021-06-30 18:57:09 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2021-07-01 11:06:07 -0700 |
| commit | fc37a3b8b4388e73e8e3525556d9f1feeb232bb9 (patch) | |
| tree | 4a1adfb461437e5dff7626b725c7f77ab11dbcae /ipc | |
| parent | 3b52348345b2cfe038d317de52bcdef788c6520d (diff) | |
| download | lwn-fc37a3b8b4388e73e8e3525556d9f1feeb232bb9.tar.gz lwn-fc37a3b8b4388e73e8e3525556d9f1feeb232bb9.zip | |
ipc sem: use kvmalloc for sem_undo allocation
Patch series "ipc: allocations cleanup", v2.
Some ipc objects use the wrong allocation functions: small objects can use
kmalloc(), and vice versa, potentially large objects can use kmalloc().
This patch (of 2):
Size of sem_undo can exceed one page and with the maximum possible nsems =
32000 it can grow up to 64Kb. Let's switch its allocation to kvmalloc to
avoid user-triggered disruptive actions like OOM killer in case of
high-order memory shortage.
User triggerable high order allocations are quite a problem on heavily
fragmented systems. They can be a DoS vector.
Link: https://lkml.kernel.org/r/ebc3ac79-3190-520d-81ce-22ad194986ec@virtuozzo.com
Link: https://lkml.kernel.org/r/a6354fd9-2d55-2e63-dd4d-fa7dc1d11134@virtuozzo.com
Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Roman Gushchin <guro@fb.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Dmitry Safonov <0x7f454c46@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Manfred Spraul <manfred@colorfullife.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'ipc')
| -rw-r--r-- | ipc/sem.c | 11 |
1 files changed, 6 insertions, 5 deletions
diff --git a/ipc/sem.c b/ipc/sem.c index bf534c74293e..3a58188733d8 100644 --- a/ipc/sem.c +++ b/ipc/sem.c @@ -1154,7 +1154,7 @@ static void freeary(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp) un->semid = -1; list_del_rcu(&un->list_proc); spin_unlock(&un->ulp->lock); - kfree_rcu(un, rcu); + kvfree_rcu(un, rcu); } /* Wake up all pending processes and let them fail with EIDRM. */ @@ -1937,7 +1937,8 @@ static struct sem_undo *find_alloc_undo(struct ipc_namespace *ns, int semid) rcu_read_unlock(); /* step 2: allocate new undo structure */ - new = kzalloc(sizeof(struct sem_undo) + sizeof(short)*nsems, GFP_KERNEL); + new = kvzalloc(sizeof(struct sem_undo) + sizeof(short)*nsems, + GFP_KERNEL); if (!new) { ipc_rcu_putref(&sma->sem_perm, sem_rcu_free); return ERR_PTR(-ENOMEM); @@ -1949,7 +1950,7 @@ static struct sem_undo *find_alloc_undo(struct ipc_namespace *ns, int semid) if (!ipc_valid_object(&sma->sem_perm)) { sem_unlock(sma, -1); rcu_read_unlock(); - kfree(new); + kvfree(new); un = ERR_PTR(-EIDRM); goto out; } @@ -1960,7 +1961,7 @@ static struct sem_undo *find_alloc_undo(struct ipc_namespace *ns, int semid) */ un = lookup_undo(ulp, semid); if (un) { - kfree(new); + kvfree(new); goto success; } /* step 5: initialize & link new undo structure */ @@ -2420,7 +2421,7 @@ void exit_sem(struct task_struct *tsk) rcu_read_unlock(); wake_up_q(&wake_q); - kfree_rcu(un, rcu); + kvfree_rcu(un, rcu); } kfree(ulp); } |