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dismantl / linux-injector

Utility for injecting executable code into a running process on x86/x64 Linux
GNU General Public License v3.0
258 stars 45 forks source link

Excess memory allocation #2

Open Smattr opened 8 years ago

Smattr commented 8 years ago

IIUC 17d4a603fc8ca330cc12f0bef0b8deb6ea3f638a modified ptrace_writemem to expect the size of its input to be word-aligned. It did this by pushing the alignment adjustment outwards into ptrace_writemem's callers. However, the new alignment adjustment is not equivalent. In particular, prior to this commit the size would not be adjusted if it was already word-aligned. Following this commit a word-aligned size is incremented by another word. I'm unsure if this was intentional or not, but it looks to me as if this extra word is unnecessary and goes unused. If you agree with this assessment and are happy to take a pull request, I can have a go at changing this to only increase the size when it's not already word-aligned. Thanks!

dismantl commented 8 years ago

You're right, it would add an extra word if the payload length was already word-aligned. Since the newly allocated payload buffer is filled with NOPs before the shellcode is copied into it, it shouldn't affect the functionality. But for the sake of code cleanliness, I'm happy to accept a pull request that fixes this. Thanks for pointing it out.