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fs: improve dump_inode() to safely access inode fields

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Use get_kernel_nofault() to safely access inode and related structures
(superblock, file_system_type) to avoid crashing when the inode pointer
is invalid. This allows the same pattern as dump_mapping().

Note: The original access method for i_state and i_count is preserved,
as get_kernel_nofault() is unnecessary once the inode structure is
verified accessible.

Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Yuto Ohnuki <ytohnuki@amazon.com>
Link: https://patch.msgid.link/20260112181443.81286-1-ytohnuki@amazon.com
Reviewed-by: Mateusz Guzik <mjguzik@gmail.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Yuto Ohnuki
2026-01-12 18:14:43 +00:00
committed by Christian Brauner
parent 58ecde96e8
commit 7c02250033
1 changed files with 34 additions and 13 deletions
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47
fs/inode.c
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@@ -2984,24 +2984,45 @@ umode_t mode_strip_sgid(struct mnt_idmap *idmap,
EXPORT_SYMBOL(mode_strip_sgid);
#ifdef CONFIG_DEBUG_VFS
/*
* Dump an inode.
/**
* dump_inode - dump an inode.
* @inode: inode to dump
* @reason: reason for dumping
*
* TODO: add a proper inode dumping routine, this is a stub to get debug off the
* ground.
*
* TODO: handle getting to fs type with get_kernel_nofault()?
* See dump_mapping() above.
* If inode is an invalid pointer, we don't want to crash accessing it,
* so probe everything depending on it carefully with get_kernel_nofault().
*/
void dump_inode(struct inode *inode, const char *reason)
{
struct super_block *sb = inode->i_sb;
struct super_block *sb;
struct file_system_type *s_type;
const char *fs_name_ptr;
char fs_name[32] = {};
umode_t mode;
unsigned short opflags;
unsigned int flags;
unsigned int state;
int count;
pr_warn("%s encountered for inode %px\n"
"fs %s mode %ho opflags 0x%hx flags 0x%x state 0x%x count %d\n",
reason, inode, sb->s_type->name, inode->i_mode, inode->i_opflags,
inode->i_flags, inode_state_read_once(inode), atomic_read(&inode->i_count));
if (get_kernel_nofault(sb, &inode->i_sb) ||
get_kernel_nofault(mode, &inode->i_mode) ||
get_kernel_nofault(opflags, &inode->i_opflags) ||
get_kernel_nofault(flags, &inode->i_flags)) {
pr_warn("%s: unreadable inode:%px\n", reason, inode);
return;
}
state = inode_state_read_once(inode);
count = atomic_read(&inode->i_count);
if (!sb ||
get_kernel_nofault(s_type, &sb->s_type) || !s_type ||
get_kernel_nofault(fs_name_ptr, &s_type->name) || !fs_name_ptr ||
strncpy_from_kernel_nofault(fs_name, fs_name_ptr, sizeof(fs_name) - 1) < 0)
strscpy(fs_name, "<unknown, sb unreadable>");
pr_warn("%s: inode:%px fs:%s mode:%ho opflags:%#x flags:%#x state:%#x count:%d\n",
reason, inode, fs_name, mode, opflags, flags, state, count);
}
EXPORT_SYMBOL(dump_inode);
#endif