From b769f49463711205d57286e64cf535ed4daf59e9 Mon Sep 17 00:00:00 2001 From: Dan Rosenberg Date: Wed, 23 Mar 2011 10:53:41 -0400 Subject: 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 Signed-off-by: Takashi Iwai --- sound/oss/opl3.c | 8 ++------ 1 file changed, 2 insertions(+), 6 deletions(-) (limited to 'sound/oss/opl3.c') diff --git a/sound/oss/opl3.c b/sound/oss/opl3.c index 938c48c43585..cbf957424d5c 100644 --- a/sound/oss/opl3.c +++ b/sound/oss/opl3.c @@ -820,7 +820,7 @@ static void opl3_hw_control(int dev, unsigned char *event) } 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 @@ static int opl3_load_patch(int dev, int format, const char __user *addr, 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) -- cgit v1.2.3