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Mark M Profile picture
@offlinemark
Aug 28, 2015 • 3 tweets • 1 min read • Read on X
Recommendations for how to efficiently prepare for @CSAW_NYUPoly while minimizing time spent/wasted struggling through challs? #ctf #infosec
I spend most of my time writing code, not exploits, b/c occasionally I'll spend a night on a ctf and literally get no flags... (1/2)

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More from @offlinemark

Mark M Profile picture
Apr 4, 2023
linux virtual memory fun fact of the day:

after a fork+exec to run a subshell, a parent process will page fault on every first write to every single writable page in its address space
it's common knowledge that after a fork(), a child has unwritable page table entries to facilitate Copy-On-Write (COW)

but in addition, the parent must also have its virtual memory completely write protected. otherwise, writes would be visible in the child
even if the child immediately execs, leaving the parent the only owner of the previously shared physical frames, the parent still has a completely write protected address space.

it will minor fault on every write access to a new page from this point on
Read 10 tweets
Mark M Profile picture
Jan 12, 2021
If you don't have anything insightful to say, it's not because you're not an "insightful person". It's because:

📖 You don't read enough
🔍 You don't reflect on your experiences
📝 You don't record ideas diligently
🌱 You don't have practice developing ideas

Thread👇
📖 You don't read enough

If you want to be an idea generation machine, you need fuel. The fuel is constructive content:

🥇 Podcasts, Books
🥈 Articles
🥉 Twitter Threads 😉

Your brain needs food to chew on.
🔍 You don't reflect on your experiences

Your everyday experiences are rich with lessons waiting for you to uncover. You just need to dig.

Make a habit of asking yourself:

"What's the takeaway here?"
"What would I do differently?"
"What advice would I give about this?"
Read 7 tweets
Mark M Profile picture
Sep 16, 2020
This tweet is ignorant, linking what make me realize this below 👇
Didn't realize that Linux is the largest, fastest moving software project, ever. Also TIL "Github scaling wall"

More detailed insight from Greg KH into the kernel dev process, with emphasis, again, on how fast they move.

Read 4 tweets
Mark M Profile picture
Jul 22, 2020
Fun fact: you can use /proc/self/mem to bypass write protections for memory pages 📝
Why does this work? Isn't the kernel subject to memory permissions? Answer: sometimes 🛡
..so what does the FOLL_FORCE flag do?

If you're ready to dive in the weeds and walk through the linux kernel with me for 45 min, keep watching😂 Covering page faults, copy on write, permission enforcement, etc

full vid:
Read 4 tweets
Mark M Profile picture
Jul 1, 2020
🤔🧐 Image
😂 Image
another night of no context c++ , aka 'mark learns about the empty base class optimization'
Read 4 tweets
Mark M Profile picture
Jun 16, 2020
I love the tone of this paper. It has the wistfulness of someone whose been on a long, long journey and has immense experience to share.
cacm.acm.org/careers/245589…
constexpr took 16 YEARS for standardization :O Image
Reasoning behind the policy to prefer adding features to the library vs the language Image
Read 8 tweets

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