diff options
author | Dan Rosenberg <drosenberg@vsecurity.com> | 2011-03-23 10:53:41 -0400 |
---|---|---|
committer | Takashi Iwai <tiwai@suse.de> | 2011-03-23 22:47:46 +0100 |
commit | b769f49463711205d57286e64cf535ed4daf59e9 (patch) | |
tree | 1c674fdbed533434d2ba9b7b1b3646243160e55c /sound/oss/midi_synth.c | |
parent | ce24f58a1187ca3058d72c3f897e3b574209ab20 (diff) | |
download | linux-stable-b769f49463711205d57286e64cf535ed4daf59e9.tar.gz linux-stable-b769f49463711205d57286e64cf535ed4daf59e9.tar.bz2 linux-stable-b769f49463711205d57286e64cf535ed4daf59e9.zip |
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>
Diffstat (limited to 'sound/oss/midi_synth.c')
-rw-r--r-- | sound/oss/midi_synth.c | 30 |
1 files changed, 13 insertions, 17 deletions
diff --git a/sound/oss/midi_synth.c b/sound/oss/midi_synth.c index 3c09374ea5bf..2292c230d7e6 100644 --- a/sound/oss/midi_synth.c +++ b/sound/oss/midi_synth.c @@ -476,7 +476,7 @@ EXPORT_SYMBOL(midi_synth_hw_control); int midi_synth_load_patch(int dev, int format, const char __user *addr, - int offs, int count, int pmgr_flag) + int count, int pmgr_flag) { int orig_dev = synth_devs[dev]->midi_dev; @@ -491,33 +491,29 @@ midi_synth_load_patch(int dev, int format, const char __user *addr, if (!prefix_cmd(orig_dev, 0xf0)) return 0; + /* Invalid patch format */ if (format != SYSEX_PATCH) - { -/* printk("MIDI Error: Invalid patch format (key) 0x%x\n", format);*/ return -EINVAL; - } + + /* Patch header too short */ if (count < hdr_size) - { -/* printk("MIDI Error: Patch header too short\n");*/ return -EINVAL; - } + count -= hdr_size; /* - * Copy the header from user space but ignore the first bytes which have - * been transferred already. + * Copy the header from user space */ - if(copy_from_user(&((char *) &sysex)[offs], &(addr)[offs], hdr_size - offs)) + if (copy_from_user(&sysex, addr, hdr_size)) return -EFAULT; - - if (count < sysex.len) - { -/* printk(KERN_WARNING "MIDI Warning: Sysex record too short (%d<%d)\n", count, (int) sysex.len);*/ + + /* Sysex record too short */ + if ((unsigned)count < (unsigned)sysex.len) sysex.len = count; - } - left = sysex.len; - src_offs = 0; + + left = sysex.len; + src_offs = 0; for (i = 0; i < left && !signal_pending(current); i++) { |