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authorLaurent Pinchart <laurent.pinchart@skynet.be>2009-01-06 17:40:40 -0500
committerLinus Torvalds <torvalds@linux-foundation.org>2009-01-06 18:59:11 -0500
commitf41ced8f108cc80f16509b907cd7ac93944459bc (patch)
treee2428887e43f26f373523be3d9ded4427a2c331f /sound
parentbdbeed75b288443ea14208eafaac3941f385f2ae (diff)
Check fops_get() return value
Several subsystem open handlers dereference the fops_get() return value without checking it for nullness. This opens a race condition between the open handler and module unloading. A module can be marked as being unloaded (MODULE_STATE_GOING) before its exit function is called and gets the chance to unregister the driver. During that window open handlers can still be called, and fops_get() will fail in try_module_get() and return a NULL pointer. This change checks the fops_get() return value and returns -ENODEV if NULL. Reported-by: Alan Jenkins <alan-jenkins@tuffmail.co.uk> Signed-off-by: Laurent Pinchart <laurent.pinchart@skynet.be> Acked-by: Takashi Iwai <tiwai@suse.de> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Dave Airlie <airlied@linux.ie> Acked-by: Mauro Carvalho Chehab <mchehab@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'sound')
-rw-r--r--sound/core/sound.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/sound/core/sound.c b/sound/core/sound.c
index 44a69bb8d4f0..7872a02f6ca9 100644
--- a/sound/core/sound.c
+++ b/sound/core/sound.c
@@ -152,6 +152,10 @@ static int __snd_open(struct inode *inode, struct file *file)
152 } 152 }
153 old_fops = file->f_op; 153 old_fops = file->f_op;
154 file->f_op = fops_get(mptr->f_ops); 154 file->f_op = fops_get(mptr->f_ops);
155 if (file->f_op == NULL) {
156 file->f_op = old_fops;
157 return -ENODEV;
158 }
155 if (file->f_op->open) 159 if (file->f_op->open)
156 err = file->f_op->open(inode, file); 160 err = file->f_op->open(inode, file);
157 if (err) { 161 if (err) {