Messages in this thread | | | From | Igor Torrente <> | Subject | Mysterious operations in sysimgblt.c and sysimgblt.c | Date | Fri, 14 May 2021 11:11:57 -0300 |
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Hello everybody,
I'm Igor, I'm participating in the Linux kernel mentorship program and working to fix some bugs found by the syzbot. I'm currently working on this bug below:
https://syzkaller.appspot.com/bug?id=071122e4f772c1ec834c7a6facc0b5058d215481
The bug consists of an out-of-bound access of an vmalloc vector at the imageblit function.
At this moment, I'm trying to understand what is happening between the IOCTL and the imageblit function. I tried to follow the commit history, but even with the entire history, and after reading the code several times, I have no clue why some operations are being done. Operations like:
Lines 148 and 177-180: https://elixir.bootlin.com/linux/v5.13-rc1/source/drivers/video/fbdev/core/bitblit.c#L148 Lines 251-256: https://elixir.bootlin.com/linux/v5.13-rc1/source/drivers/video/fbdev/core/sysimgblt.c#L251 Line 190: https://elixir.bootlin.com/linux/v5.13-rc1/source/drivers/video/fbdev/core/sysimgblt.c#L190
Anyone know/remember what these operations are doing?
Thanks for your attention, --- Igor M. A. Torrente
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