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Add limit parameter to decompressZlib

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This can prevent untrusted data, such as sent over the network,
from consuming all memory with a specially crafted payload.
This commit is contained in:
Ben Deutsch 2018-01-30 22:12:40 +01:00 • committed by sfan5
parent 1116918dbb
commit 2b3490db1f
3 changed files with 81 additions and 4 deletions
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20
src/serialization.cpp
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@ -99,7 +99,7 @@ void compressZlib(const std::string &data, std::ostream &os, int level)
compressZlib((u8*)data.c_str(), data.size(), os, level);
}
void decompressZlib(std::istream &is, std::ostream &os)
void decompressZlib(std::istream &is, std::ostream &os, size_t limit)
{
z_stream z;
const s32 bufsize = 16384;
@ -108,6 +108,7 @@ void decompressZlib(std::istream &is, std::ostream &os)
int status = 0;
int ret;
int bytes_read = 0;
int bytes_written = 0;
int input_buffer_len = 0;
z.zalloc = Z_NULL;
@ -124,8 +125,20 @@ void decompressZlib(std::istream &is, std::ostream &os)
for(;;)
{
int output_size = bufsize;
z.next_out = (Bytef*)output_buffer;
z.avail_out = bufsize;
z.avail_out = output_size;
if (limit) {
int limit_remaining = limit - bytes_written;
if (limit_remaining <= 0) {
// we're aborting ahead of time - throw an error?
break;
}
if (limit_remaining < output_size) {
z.avail_out = output_size = limit_remaining;
}
}
if(z.avail_in == 0)
{
@ -153,10 +166,11 @@ void decompressZlib(std::istream &is, std::ostream &os)
zerr(status);
throw SerializationError("decompressZlib: inflate failed");
}
int count = bufsize - z.avail_out;
int count = output_size - z.avail_out;
//dstream<<"count="<<count<<std::endl;
if(count)
os.write(output_buffer, count);
bytes_written += count;
if(status == Z_STREAM_END)
{
//dstream<<"Z_STREAM_END"<<std::endl;