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smacker: limit recursion depth of smacker_decode_bigtree

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This fixes segmentation faults due to stack-overflow caused by too deep
recursion.

Reviewed-by: Michael Niedermayer <michael@niedermayer.cc>
Signed-off-by: Andreas Cadhalpun <Andreas.Cadhalpun@googlemail.com>
This commit is contained in:
Andreas Cadhalpun 2016-11-19 14:21:11 +01:00
parent 4e5049a230
commit 946ecd19ea
1 changed files with 8 additions and 4 deletions
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12
libavcodec/smacker.c
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@ -129,8 +129,12 @@ static int smacker_decode_tree(GetBitContext *gb, HuffContext *hc, uint32_t pref
/**
* Decode header tree
*/
static int smacker_decode_bigtree(GetBitContext *gb, HuffContext *hc, DBCtx *ctx)
static int smacker_decode_bigtree(GetBitContext *gb, HuffContext *hc, DBCtx *ctx, int length)
{
if(length > 500) { // Larger length can cause segmentation faults due to too deep recursion.
av_log(NULL, AV_LOG_ERROR, "length too long\n");
return AVERROR_INVALIDDATA;
}
if (hc->current + 1 >= hc->length) {
av_log(NULL, AV_LOG_ERROR, "Tree size exceeded!\n");
return AVERROR_INVALIDDATA;
@ -159,12 +163,12 @@ static int smacker_decode_bigtree(GetBitContext *gb, HuffContext *hc, DBCtx *ctx
int r = 0, r_new, t;
t = hc->current++;
r = smacker_decode_bigtree(gb, hc, ctx);
r = smacker_decode_bigtree(gb, hc, ctx, length + 1);
if(r < 0)
return r;
hc->values[t] = SMK_NODE | r;
r++;
r_new = smacker_decode_bigtree(gb, hc, ctx);
r_new = smacker_decode_bigtree(gb, hc, ctx, length + 1);
if (r_new < 0)
return r_new;
return r + r_new;
@ -275,7 +279,7 @@ static int smacker_decode_header_tree(SmackVContext *smk, GetBitContext *gb, int
goto error;
}
if (smacker_decode_bigtree(gb, &huff, &ctx) < 0)
if (smacker_decode_bigtree(gb, &huff, &ctx, 0) < 0)
err = -1;
skip_bits1(gb);
if(ctx.last[0] == -1) ctx.last[0] = huff.current++;