__clear_user(9)

✨ __clear_user(9) ✨

okay so this page is from the Kernel API Manual, and it's giving "small function, big responsibility" energy. Let's go 💅

🌸 NAME 🌸

• __clear_user — Zero a block of memory in user space, with less checking.

🦋 SYNOPSIS 🦋

unsigned long __clear_user (void __user *to , unsigned long n );

🎀 ARGUMENTS 🎀

• to — Destination address, in user space.
• n — Number of bytes to zero.

💖 DESCRIPTION 💖

Zero a block of memory in user space. That's the whole vibe: you point at a user-space block, you say how many bytes, and it clears them.

bestie, read this part twice: the caller must check the specified block with access_ok before calling this function. That's the "less checking" part in the name — do not skip your access_ok check, fr fr. 🫶

🔥 RETURN 🔥

It returns the number of bytes that could not be cleared. On success, this will be zero. So if you get 0, slay; if not, that's the count of bytes that didn't get cleared. 💀

🌈 SEE ALSO 🌈

• Kernel file ./arch/x86/lib/usercopy_32.c
• clear_user(9)

okay bye bestie — this one's from ./arch/x86/lib, dated October 2026, and it's the __clear_user(9) page 💖✨