1462191 - nestegg: unsigned integer overflow in [@ ne_read_ebml_lacing]

Status: NEW

(Core :: Audio/Video: Playback, defect, P3)

Description

[Tyson Smith [:tsmith]]

Attachment: testcase.webm

nestegg (test) was build unsing the following config command:
CFLAGS="-fsanitize=integer" CC=clang ./configure --enable-static --disable-shared

src/nestegg.c:1491:33: runtime error: unsigned integer overflow: 0 - 4 cannot be represented in type 'unsigned long'
    #0 0x504a87 in ne_read_ebml_lacing nestegg/src/nestegg.c:1305:28
    #1 0x504a87 in ne_read_block nestegg/src/nestegg.c:1509
    #2 0x4fdf38 in nestegg_read_packet nestegg/src/nestegg.c:2802:15
    #3 0x4ea703 in main nestegg/test/test.c:166:9
    #4 0x7f09dfbe282f in __libc_start_main /build/glibc-Cl5G7W/glibc-2.23/csu/../csu/libc-start.c:291
    #5 0x418928 in _start (nestegg/test+0x418928)

Comment 1

[Matthew Gregan [:kinetik]]

In terms of security, comments 1-3 from bug 1462189 apply for this one too.  I believe it's safe, so clearing s-s.

To fix this case, we can probably just check for overflow and treat the media as invalid with an error, since reading an invalid block size is likely to result in the parser losing sync and treating the media as invalid later anyway.