sound/oss: remove offset from load_patch callbacks
Was: [PATCH] sound/oss/midi_synth: prevent underflow, use of
uninitialized value, and signedness issue
The offset passed to midi_synth_load_patch() can be essentially
arbitrary. If it's greater than the header length, this will result in
a copy_from_user(dst, src, negative_val). While this will just return
-EFAULT on x86, on other architectures this may cause memory corruption.
Additionally, the length field of the sysex_info structure may not be
initialized prior to its use. Finally, a signed comparison may result
in an unintentionally large loop.
On suggestion by Takashi Iwai, version two removes the offset argument
from the load_patch callbacks entirely, which also resolves similar
issues in opl3. Compile tested only.
v3 adjusts comments and hopefully gets copy offsets right.
Signed-off-by: Dan Rosenberg <drosenberg@vsecurity.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/oss/opl3.c b/sound/oss/opl3.c
index 938c48c..cbf9574 100644
--- a/sound/oss/opl3.c
+++ b/sound/oss/opl3.c
@@ -820,7 +820,7 @@
}
static int opl3_load_patch(int dev, int format, const char __user *addr,
- int offs, int count, int pmgr_flag)
+ int count, int pmgr_flag)
{
struct sbi_instrument ins;
@@ -830,11 +830,7 @@
return -EINVAL;
}
- /*
- * What the fuck is going on here? We leave junk in the beginning
- * of ins and then check the field pretty close to that beginning?
- */
- if(copy_from_user(&((char *) &ins)[offs], addr + offs, sizeof(ins) - offs))
+ if (copy_from_user(&ins, addr, sizeof(ins)))
return -EFAULT;
if (ins.channel < 0 || ins.channel >= SBFM_MAXINSTR)