In flt_readdir(), do not write into the buffer returned by readdir() #1
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When adjusting file names, flt_readdir() assumes that the de->d_name points to a buffer that has sufficient size to accomodate the new name. However, readdir() does not makes any guarantee about that at all. In practice, I've seen de->d_name pointing to tightly packed memory, such that overwriting past the original name ends up corrupting data in the directory stream, leading to erratic undefined behavior. (In my case, the directory offset became corrupted, leading to an infinite directory scanning loop.) This commit fixes the issue by copying the name into some local buffer before making changes to it. Also, I took the liberty to sprinkle some more debug statements while I'm at it.
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When adjusting file names,
flt_readdir()assumes thatde->d_namepoints to a buffer that has sufficient size to accommodate the new name. However,readdir()does not makes any guarantee about that at all.In practice, I've seen
de->d_namepointing to tightly packed memory, such that overwriting past the original name ends up corrupting data in the directory stream, leading to erratic undefined behaviour. (In my case, the directory offset became corrupted, leading to an infinite directory scanning loop.)This commit fixes the issue by copying the name into some local buffer before making changes to it. Also, I took the liberty to sprinkle some more debug statements while I'm at it.