[PATCH 5.14 046/162] comedi: Fix memory leak in compat_insnlist()

From: Greg Kroah-Hartman
Date: Mon Sep 27 2021 - 13:21:34 EST

From: Ian Abbott <abbotti@xxxxxxxxx>

commit bb509a6ffed2c8b0950f637ab5779aa818ed1596 upstream.

`compat_insnlist()` handles the 32-bit version of the `COMEDI_INSNLIST`
ioctl (whenwhen `CONFIG_COMPAT` is enabled). It allocates memory to
temporarily hold an array of `struct comedi_insn` converted from the
32-bit version in user space. This memory is only being freed if there
is a fault while filling the array, otherwise it is leaked.

Add a call to `kfree()` to fix the leak.

Fixes: b8d47d881305 ("comedi: get rid of compat_alloc_user_space() mess in COMEDI_INSNLIST compat")
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: linux-staging@xxxxxxxxxxxxxxx
Cc: <stable@xxxxxxxxxxxxxxx> # 5.13+
Signed-off-by: Ian Abbott <abbotti@xxxxxxxxx>
Link: https://lore.kernel.org/r/20210916145023.157479-1-abbotti@xxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
drivers/comedi/comedi_fops.c | 1 +
1 file changed, 1 insertion(+)

--- a/drivers/comedi/comedi_fops.c
+++ b/drivers/comedi/comedi_fops.c
@@ -3090,6 +3090,7 @@ static int compat_insnlist(struct file *
rc = do_insnlist_ioctl(dev, insns, insnlist32.n_insns, file);
+ kfree(insns);
return rc;