Masanori Ogino 𓀁 omasanori@mstdn.maud.io
カムヤライド / 久正人 http://seiga.nicovideo.jp/comic/37280 #ニコニコ漫画
カ、カメンライド……
Masanori Ogino 𓀁 reblogged at 6 years ago
神父牧師 Otakyuline
ものによっては多分並行していろんな手を評価してるだろうからスレッド数は関係ありそう
Masanori Ogino 𓀁 reblogged at 6 years ago
Masanori Ogino 𓀁 reblogged at 6 years ago
無宛(insane)@EmoticPowerPlant✅ LwVe9@mstdn.jp
え、藤井七段ってAMDerなの
Masanori Ogino 𓀁 reblogged at 6 years ago
Togetter(RSSfeed) togetter@chaosphere.hostdon.jp
【 #Togetter 注目のまとめ #RSSfeed 】
藤井七段、AMDのCPUに言及
https://togetter.com/li/1293954
Masanori Ogino 𓀁 reblogged at 6 years ago
otto@openbsd otto@bsd.network
Why does #OpenBSD's #malloc do so much randomization? 1) to catch bugs. If you memory layout differs each run, bugs that would otherwise be hidden are exposed. 2) it makes lives of attackers harder. They cannot rely on certain allocations always to be next to each other.
Masanori Ogino 𓀁 reblogged at 6 years ago
otto@openbsd otto@bsd.network
A common bug is to leave sensitive mem uncleared and reuse memory (e.g. via #malloc’s cache) without proper initialisation, leading to secret leakage. The purpose of freezero() and recallocarray() is to protect against that threat. Big threat to the application is the application.
Masanori Ogino 𓀁 reblogged at 6 years ago
otto@openbsd otto@bsd.network
#malloc is a general purpose allocator. If you know more about your typical memory usage, you can probably write a faster special purpose allocator. But wait with writing your own until you have evidence that malloc is the bottleneck, remember the features of #OpenBSD's malloc.
Masanori Ogino 𓀁 reblogged at 6 years ago
otto@openbsd otto@bsd.network
Sensitive data? memset(p, 0, sz); free(p); does not do want you think it does. The compiler is allowed to optimise the memset away. Use freezero(p, sz). For large allocations #OpenBSD just unmaps the pages, avoiding the clearing and still making the memory inaccessible.
Masanori Ogino 𓀁 reblogged at 6 years ago
otto@openbsd otto@bsd.network
A lot of malloc implementations hold on to memory pages received from the kernel. #openbsd's #malloc is reasonably aggressive with unmapping pages that are unused, catching use-after-free bugs with segmentation violations.
Masanori Ogino 𓀁 reblogged at 6 years ago
otto@openbsd otto@bsd.network
#openbsd's #malloc stores meta-data separated from the memory returned to the caller, making it harder to use heap overflows to achieve code injection and execution. See e.g. http://www.mathyvanhoef.com/2013/02/understanding-heap-exploiting-heap.html … and references. Having malloc meta-data near program data is dangerous!
Masanori Ogino 𓀁 reblogged at 6 years ago
Masanori Ogino 𓀁 reblogged at 6 years ago