Blame SOURCES/0419-video-readers-jpeg-Test-for-an-invalid-next-marker-r.patch

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From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Darren Kenny <darren.kenny@oracle.com>
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Date: Fri, 4 Dec 2020 15:39:00 +0000
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Subject: [PATCH] video/readers/jpeg: Test for an invalid next marker reference
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 from a jpeg file
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While it may never happen, and potentially could be caught at the end of
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the function, it is worth checking up front for a bad reference to the
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next marker just in case of a maliciously crafted file being provided.
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Fixes: CID 73694
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Signed-off-by: Darren Kenny <darren.kenny@oracle.com>
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Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
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---
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 grub-core/video/readers/jpeg.c | 6 ++++++
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 1 file changed, 6 insertions(+)
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diff --git a/grub-core/video/readers/jpeg.c b/grub-core/video/readers/jpeg.c
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index 31359a4c9..0b6ce3cee 100644
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--- a/grub-core/video/readers/jpeg.c
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+++ b/grub-core/video/readers/jpeg.c
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@@ -253,6 +253,12 @@ grub_jpeg_decode_quan_table (struct grub_jpeg_data *data)
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   next_marker = data->file->offset;
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   next_marker += grub_jpeg_get_word (data);
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+  if (next_marker > data->file->size)
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+    {
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+      /* Should never be set beyond the size of the file. */
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+      return grub_error (GRUB_ERR_BAD_FILE_TYPE, "jpeg: invalid next reference");
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+    }
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+
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   while (data->file->offset + sizeof (data->quan_table[id]) + 1
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 	 <= next_marker)
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     {