__kmemdup_nul(9)

💖 __kmemdup_nul — Kernel API Manual, but make it make sense 💖

okay so bestie, welcome to the <pink>Kernel API Manual</pink> entry for __kmemdup_nul(9) — yes the double-underscore one, she's the ✨internal✨ girlie, put some respect on her name 🎀

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🌸 NAME 🌸

__kmemdup_nul — creates a NUL-terminated string from @s, which might be unterminated 😱

like, @s might just rawdog its way to the end with no \0 in sight, and this function is the one that shows up with a little terminator for her 🫶

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✨ SYNOPSIS ✨

char * __kmemdup_nul (const char *s , size_t len , gfp_t gfp );

that's the whole vibe check right there 💅

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🦋 ARGUMENTS 🦋

• s — the data to copy. literally the payload, the main character, the whole reason we're here 👑
• len — the size of the data, and no bestie, this does not include the NUL terminator, so don't be out here counting her 🙈
• gfp — the GFP mask used in the kmalloc call when allocating memory. it's giving "how do you want this allocation to go down" energy ⭐

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💜 RETURN 💜

you get back a newly allocated copy of s with NUL-termination — slay 🎉 — or NULL in case of error 😭 so like, check your return values, fr fr, no cap, this is the moment where NULL checks are non-negotiable 💀

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🌈 SEE ALSO 🌈

ok so this is the friend group, everybody's tagged 🫶

Kernel file ./mm/util.c

then, in the order the manpage hands them to us, no reshuffling, no skipping:

• kfree_const(9)
• kstrdup(9)
• kstrdup_const(9)
• kstrndup(9)
• kmemdup(9)
• kmemdup_array(9)
• kvmemdup(9)
• kmemdup_nul(9)
• memdup_user(9)
• vmemdup_user(9)
• strndup_user(9)
• memdup_user_nul(9)
• randomize_page(9)
• __account_locked_vm(9)
• account_locked_vm(9)
• __vmalloc_array(9)
• vmalloc_array(9)
• __vcalloc(9)
• vcalloc(9)
• folio_mapping(9)
• folio_copy(9)
• get_cmdline(9)
• mem_dump_obj(9)
• compat_set_desc_from_vma(9)
• __compat_vma_mmap(9)
• compat_vma_mmap(9)
• snapshot_page(9)
• mmap_action_prepare(9)
• mmap_action_complete(9)
• folio_pte_batch(9)
• page_range_contiguous(9)

💡 no seriously, that's all of them, don't @ me, I didn't invent a single one and I didn't drop a single one either 🔥

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and that's the page, bestie! 💅 tiny little note before I go — this one lives in the ./mm section, dated October 2026, and it's filed under the header __kmemdup_nul(9) in the <purple>Kernel API Manual</purple>. go forth and terminate your strings properly, mwah 😘🎀✨