From 18698b35b48bd6198c576d889bec70c50acf5758 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Fri, 10 Jul 2026 11:33:12 +0200 Subject: [PATCH] binfmt_misc: use print_hex_dump_debug() for the register debug output The hex dumps in create_entry() are compiled out unless someone edits the file to define DEBUG while the pr_debug() calls right next to them are dynamic-debug aware. Switch the dumps to print_hex_dump_debug() which follows the same rules as pr_debug() so the register parsing debug output is uniformly controlled through dynamic debug, and remove the USE_DEBUG machinery. Drop the magic[masked] dump instead of converting it: it printed the bitwise AND of two buffers dumped right above it and required a temporary allocation on every registration just to recompute what the reader can derive from the magic and mask dumps directly. Link: https://patch.msgid.link/20260710-work-binfmt_misc-locking-v3-11-a162f7cb58d6@kernel.org Reviewed-by: Jori Koolstra Signed-off-by: Christian Brauner (Amutable) --- fs/binfmt_misc.c | 52 ++++++++++++++---------------------------------- 1 file changed, 15 insertions(+), 37 deletions(-) diff --git a/fs/binfmt_misc.c b/fs/binfmt_misc.c index 0880b058d3b6..ab715618142e 100644 --- a/fs/binfmt_misc.c +++ b/fs/binfmt_misc.c @@ -32,12 +32,6 @@ #include "internal.h" -#ifdef DEBUG -# define USE_DEBUG 1 -#else -# define USE_DEBUG 0 -#endif - /* Entry status and match type bit numbers. */ enum binfmt_misc_entry_bits { MISC_FMT_ENABLED_BIT = 0, @@ -459,10 +453,9 @@ static struct binfmt_misc_entry *create_entry(const char __user *buffer, goto einval; if (!e->magic[0]) goto einval; - if (USE_DEBUG) - print_hex_dump_bytes( - KBUILD_MODNAME ": register: magic[raw]: ", - DUMP_PREFIX_NONE, e->magic, p - e->magic); + print_hex_dump_debug( + KBUILD_MODNAME ": register: magic[raw]: ", + DUMP_PREFIX_NONE, 16, 1, e->magic, p - e->magic, true); /* Parse the 'mask' field. */ e->mask = p; @@ -472,10 +465,12 @@ static struct binfmt_misc_entry *create_entry(const char __user *buffer, if (!e->mask[0]) { e->mask = NULL; pr_debug("register: mask[raw]: none\n"); - } else if (USE_DEBUG) - print_hex_dump_bytes( + } else { + print_hex_dump_debug( KBUILD_MODNAME ": register: mask[raw]: ", - DUMP_PREFIX_NONE, e->mask, p - e->mask); + DUMP_PREFIX_NONE, 16, 1, e->mask, p - e->mask, + true); + } /* * Decode the magic & mask fields. @@ -491,30 +486,13 @@ static struct binfmt_misc_entry *create_entry(const char __user *buffer, BINPRM_BUF_SIZE - e->size < e->offset) goto einval; pr_debug("register: magic/mask length: %i\n", e->size); - if (USE_DEBUG) { - print_hex_dump_bytes( - KBUILD_MODNAME ": register: magic[decoded]: ", - DUMP_PREFIX_NONE, e->magic, e->size); - - if (e->mask) { - int i; - char *masked = kmalloc(e->size, GFP_KERNEL_ACCOUNT); - - print_hex_dump_bytes( - KBUILD_MODNAME ": register: mask[decoded]: ", - DUMP_PREFIX_NONE, e->mask, e->size); - - if (masked) { - for (i = 0; i < e->size; ++i) - masked[i] = e->magic[i] & e->mask[i]; - print_hex_dump_bytes( - KBUILD_MODNAME ": register: magic[masked]: ", - DUMP_PREFIX_NONE, masked, e->size); - - kfree(masked); - } - } - } + print_hex_dump_debug( + KBUILD_MODNAME ": register: magic[decoded]: ", + DUMP_PREFIX_NONE, 16, 1, e->magic, e->size, true); + if (e->mask) + print_hex_dump_debug( + KBUILD_MODNAME ": register: mask[decoded]: ", + DUMP_PREFIX_NONE, 16, 1, e->mask, e->size, true); } else { /* Handle the 'E' (extension) format. */