A potential Integer Overflow bug found in aplay/aplay.c

[x14ngch3n]

Hi, I'm currently trying to use the static analysis tool Infer to find uncatched API-misuse bugs in OpenWrt packages, and I find a potential Integer Overflow in your project, version 1.2.9.

The bug located in aplay/aplay.c. Firstly, the program tries to write the remains bytes in audiobuf with the length of loaded in line 2865, and loaded is later used as the parameter for safe_read in the loop, then loaded is used as the 2nd argument of pct_write() and finally after a multiply operation, it is used as the size of Malloc in remap_data(), as shown in the following code:

static void playback_go(int fd, size_t loaded, off_t count, int rtype, char *name)
{
int l, r;
off_t written = 0;
off_t c;

header(rtype, name);
set_params();

while (loaded > chunk_bytes && written < count && !in_aborting) {
	if (pcm_write(audiobuf + written, chunk_size) <= 0)
		return;
	written += chunk_bytes;
	loaded -= chunk_bytes;
}
if (written > 0 && loaded > 0)
	memmove(audiobuf, audiobuf + written, loaded);

l = loaded;
while (written < count && !in_aborting) {
	do {
		c = count - written;
		if (c > chunk_bytes)
			c = chunk_bytes;

		/* c < l, there is more data loaded
			* then we actually need to write
			*/
		if (c < l)
			l = c;

		c -= l;

		if (c == 0)
			break;
		r = safe_read(fd, audiobuf + l, c);
		if (r < 0) {
			perror(name);
			prg_exit(EXIT_FAILURE);
		}
		fdcount += r;
		if (r == 0)
			break;
		l += r;
	} while ((size_t)l < chunk_bytes);
	l = l * 8 / bits_per_frame;
	r = pcm_write(audiobuf, l);
	if (r != l)
		break;
	r = r * bits_per_frame / 8;
	written += r;
	l = 0;
}
if (!in_aborting) {
	snd_pcm_nonblock(handle, 0);
	snd_pcm_drain(handle);
	snd_pcm_nonblock(handle, nonblock);
}
}

# in remap_data()
chunk_bytes = count * bits_per_frame / 8;
if (tmp_size < chunk_bytes) {
	free(tmp);
	tmp = malloc(chunk_bytes);
	if (!tmp) {
		error(_("not enough memory"));
		exit(1);
	}
	tmp_size = count;
}

The parameter passed to Malloc may be overflowed so that the actual allocated memory is small.

I also attached the analysis trace given by Infer FYI:

 "trace": [
{
	"file": "aplay/aplay.c",
	"line": 940,
	"col": 14,
	"feature": [ "Input", "read" ]
},
{
	"file": "aplay/aplay.c",
	"line": 940,
	"col": 14,
	"feature": [ "Input", "read" ]
},
{
	"file": "aplay/aplay.c",
	"line": 2865,
	"col": 21,
	"feature": [
	"Prune",
	[
		"UnOp",
		"!",
		[
		"BinOp",
		">",
		[ "Var" ],
		[ "Cast", [ "Unsupported" ], [ "Const", [ "Cint", 0 ] ] ]
		]
	]
	]
},
{
	"file": "aplay/aplay.c",
	"line": 2868,
	"col": 2,
	"feature": [ "Store", [ "Var" ], [ "Var" ] ]
},
{
	"file": "aplay/aplay.c",
	"line": 2878,
	"col": 8,
	"feature": [
	"Prune",
	[ "UnOp", "!", [ "BinOp", "<", [ "Var" ], [ "Var" ] ] ]
	]
},
{
	"file": "aplay/aplay.c",
	"line": 2871,
	"col": 4,
	"feature": [
	"Store",
	[ "Var" ],
	[ "BinOp", "-", [ "Var" ], [ "Var" ] ]
	]
},
{
	"file": "aplay/aplay.c",
	"line": 2872,
	"col": 8,
	"feature": [
	"Prune",
	[
		"UnOp",
		"!",
		[
		"BinOp",
		">",
		[ "Cast", [ "Unsupported" ], [ "Var" ] ],
		[ "Var" ]
		]
	]
	]
},
{
	"file": "aplay/aplay.c",
	"line": 2878,
	"col": 8,
	"feature": [ "Prune", [ "BinOp", "<", [ "Var" ], [ "Var" ] ] ]
},
{
	"file": "aplay/aplay.c",
	"line": 2879,
	"col": 5,
	"feature": [ "Store", [ "Var" ], [ "Var" ] ]
},
{
	"file": "aplay/aplay.c",
	"line": 2899,
	"col": 3,
	"feature": [
	"Store",
	[ "Var" ],
	[
		"BinOp",
		"/",
		[
		"BinOp",
		"*",
		[ "Cast", [ "Unsupported" ], [ "Var" ] ],
		[ "Var" ]
		],
		[ "Cast", [ "Unsupported" ], [ "Const", [ "Cint", 8 ] ] ]
	]
	]
},
{
	"file": "aplay/aplay.c",
	"line": 2900,
	"col": 3,
	"feature": [
	"Store",
	[ "Var" ],
	[ "BinOp", "+", [ "Var" ], [ "Var" ] ]
	]
},
{
	"file": "aplay/aplay.c",
	"line": 2871,
	"col": 4,
	"feature": [
	"Store",
	[ "Var" ],
	[ "BinOp", "-", [ "Var" ], [ "Var" ] ]
	]
},
{
	"file": "aplay/aplay.c",
	"line": 2872,
	"col": 8,
	"feature": [
	"Prune",
	[
		"UnOp",
		"!",
		[
		"BinOp",
		">",
		[ "Cast", [ "Unsupported" ], [ "Var" ] ],
		[ "Var" ]
		]
	]
	]
},
{
	"file": "aplay/aplay.c",
	"line": 2878,
	"col": 8,
	"feature": [ "Prune", [ "BinOp", "<", [ "Var" ], [ "Var" ] ] ]
},
{
	"file": "aplay/aplay.c",
	"line": 2879,
	"col": 5,
	"feature": [ "Store", [ "Var" ], [ "Var" ] ]
},
{
	"file": "aplay/aplay.c",
	"line": 2895,
	"col": 3,
	"feature": [
	"Store",
	[ "Var" ],
	[
		"BinOp",
		"/",
		[
		"Cast",
		[ "Unsupported" ],
		[ "BinOp", "*", [ "Var" ], [ "Const", [ "Cint", 8 ] ] ]
		],
		[ "Var" ]
	]
	]
},
{
	"file": "aplay/aplay.c",
	"line": 2896,
	"col": 7,
	"feature": [ "Call", "pcm_write" ]
},
{
	"file": "aplay/aplay.c",
	"line": 2126,
	"col": 6,
	"feature": [
	"Prune",
	[ "UnOp", "!", [ "BinOp", "<", [ "Var" ], [ "Var" ] ] ]
	]
},
{
	"file": "aplay/aplay.c",
	"line": 2130,
	"col": 9,
	"feature": [ "Call", "remap_data" ]
},
{
	"file": "aplay/aplay.c",
	"line": 2069,
	"col": 2,
	"feature": [
	"Store",
	[ "Var" ],
	[
		"BinOp",
		"/",
		[ "BinOp", "*", [ "Var" ], [ "Var" ] ],
		[ "Cast", [ "Unsupported" ], [ "Const", [ "Cint", 8 ] ] ]
	]
	]
},
{
	"file": "aplay/aplay.c",
	"line": 2070,
	"col": 6,
	"feature": [ "Prune", [ "BinOp", "<", [ "Var" ], [ "Var" ] ] ]
},
{
	"file": "aplay/aplay.c",
	"line": 2072,
	"col": 9,
	"feature": [ "IntOverflow", "malloc", [ "Var" ] ]
}
],