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From 7b1572b1772dc92b2e73b7cf6d51dca88a60f411 Mon Sep 17 00:00:00 2001
From: Pierre Joye <pierre.php@gmail.com>
Date: Tue, 19 Jul 2016 07:11:44 +0700
Subject: [PATCH] fix #72519, possible OOB using imagegif
fix #72519, possible OOB using imagegif
---
ext/gd/libgd/gd_gif_out.c | 18 ++++++++++++++++--
1 file changed, 16 insertions(+), 2 deletions(-)
diff --git a/ext/gd/libgd/gd_gif_out.c b/ext/gd/libgd/gd_gif_out.c
index 1404538..0178dd9 100644
--- a/ext/gd/libgd/gd_gif_out.c
+++ b/ext/gd/libgd/gd_gif_out.c
@@ -601,14 +601,26 @@ compress(int init_bits, gdIOCtxPtr outfile, gdImagePtr im, GifCtx *ctx)
* code in turn. When the buffer fills up empty it and start over.
*/
-static unsigned long masks[] = { 0x0000, 0x0001, 0x0003, 0x0007, 0x000F,
+static const unsigned long masks[] = { 0x0000, 0x0001, 0x0003, 0x0007, 0x000F,
0x001F, 0x003F, 0x007F, 0x00FF,
0x01FF, 0x03FF, 0x07FF, 0x0FFF,
0x1FFF, 0x3FFF, 0x7FFF, 0xFFFF };
+
+/* Arbitrary value to mark output is done. When we see EOFCode, then we don't
+ * expect to see any more data. If we do (e.g. corrupt image inputs), cur_bits
+ * might be negative, so flag it to return early.
+ */
+#define CUR_BITS_FINISHED -1000
+
+
static void
output(code_int code, GifCtx *ctx)
{
+ if (ctx->cur_bits == CUR_BITS_FINISHED) {
+ return;
+ }
+
ctx->cur_accum &= masks[ ctx->cur_bits ];
if( ctx->cur_bits > 0 )
@@ -655,8 +667,10 @@ output(code_int code, GifCtx *ctx)
ctx->cur_bits -= 8;
}
- flush_char(ctx);
+ /* Flag that it's done to prevent re-entry. */
+ ctx->cur_bits = CUR_BITS_FINISHED;
+ flush_char(ctx);
}
}
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