Abootimg sometimes extracts corrupted stage2 images

[Dmitry 'MAD' Artamonow]

On Ubuntu 16.04, abootimg-0.6-1 sometimes produces corrupted stage2 images during extraction of Android bootimage. I cannot share real boot images that exhibit this problem, but here's artificial way to reproduce it:

$ yes "KERNEL " | dd of=kern.src bs=1 count=5000
5000+0 records in
5000+0 records out
5000 bytes (5.0 kB) copied, 0.00548857 s, 911 kB/s
$ yes "RAMDISK" | dd of=ramd.src bs=1 count=5000
5000+0 records in
5000+0 records out
5000 bytes (5.0 kB) copied, 0.0186445 s, 268 kB/s
$ yes "STAGE 2" | dd of=s2.src bs=1 count=5000
5000+0 records in
5000+0 records out
5000 bytes (5.0 kB) copied, 0.0157602 s, 317 kB/s
$ hexdump -C kern.src
00000000 4b 45 52 4e 45 4c 20 0a 4b 45 52 4e 45 4c 20 0a |KERNEL .KERNEL .|
*
00001388
$ hexdump -C ramd.src
00000000 52 41 4d 44 49 53 4b 0a 52 41 4d 44 49 53 4b 0a |RAMDISK.RAMDISK.|
*
00001388
$ hexdump -C s2.src
00000000 53 54 41 47 45 20 32 0a 53 54 41 47 45 20 32 0a |STAGE 2.STAGE 2.|
*
00001388
$ abootimg --create boot.img -k kern.src -r ramd.src -s s2.src
reading kernel from kern.src
reading ramdisk from ramd.src
reading second stage from s2.src
Writing Boot Image boot.img
$ abootimg -x boot.img
writing boot image config in bootimg.cfg
extracting kernel in zImage
extracting ramdisk in initrd.img
extracting second stage image in stage2.img
$ hexdump -C stage2.img
00000000 52 41 4d 44 49 53 4b 0a 52 41 4d 44 49 53 4b 0a |RAMDISK.RAMDISK.|
*
00000380 52 41 4d 44 49 53 4b 0a 00 00 00 00 00 00 00 00 |RAMDISK.........|
00000390 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
*
00000800 53 54 41 47 45 20 32 0a 53 54 41 47 45 20 32 0a |STAGE 2.STAGE 2.|
*
00001388
$

I've looked into sources and found that offset may be calculated incorrectly due to wrong rounding (as you may see STAGE 2 text begins at offset 0x800 - size of one block). You may find fix that I use in attachment.

[Ubuntu Foundations Team Bug Bot (crichton)]

The attachment "0001-Fix-extraction-of-stage2-image.patch" seems to be a patch. If it isn't, please remove the "patch" flag from the attachment, remove the "patch" tag, and if you are a member of the ~ubuntu-reviewers, unsubscribe the team.

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