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SUSE:SLE-15-SP1:Update
grub2.26833
0004-video-readers-jpeg-Catch-OOB-reads-writes-...
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File 0004-video-readers-jpeg-Catch-OOB-reads-writes-in-grub_jp.patch of Package grub2.26833
From d80ad6a42ebc01314ac1cd8ebd7bbe01fea0974f Mon Sep 17 00:00:00 2001 From: Daniel Axtens <dja@axtens.net> Date: Fri, 15 Jan 2021 13:29:53 +1100 Subject: [PATCH 04/33] video/readers/jpeg: Catch OOB reads/writes in grub_jpeg_decode_du() The key line is: du[jpeg_zigzag_order[pos]] = val * (int) data->quan_table[qt][pos]; jpeg_zigzag_order is grub_uint8_t[64]. I don't understand JPEG decoders quite well enough to explain what's going on here. However, I observe sometimes pos=64, which leads to an OOB read of the jpeg_zigzag_order global then an OOB write to du. That leads to various unpleasant memory corruption conditions. Catch where pos >= ARRAY_SIZE(jpeg_zigzag_order) and bail. Signed-off-by: Daniel Axtens <dja@axtens.net> Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com> --- grub-core/video/readers/jpeg.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/grub-core/video/readers/jpeg.c b/grub-core/video/readers/jpeg.c index 856573996a..28c1d62515 100644 --- a/grub-core/video/readers/jpeg.c +++ b/grub-core/video/readers/jpeg.c @@ -526,6 +526,14 @@ grub_jpeg_decode_du (struct grub_jpeg_data *data, int id, jpeg_data_unit_t du) val = grub_jpeg_get_number (data, num & 0xF); num >>= 4; pos += num; + + if (pos >= ARRAY_SIZE (jpeg_zigzag_order)) + { + grub_error (GRUB_ERR_BAD_FILE_TYPE, + "jpeg: invalid position in zigzag order!?"); + return; + } + du[jpeg_zigzag_order[pos]] = val * (int) data->quan_table[qt][pos]; pos++; } -- 2.34.1
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