linux-kernel - Re: [syzbot] [ext4?] kernel BUG in ext4_write_inline

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Message-ID: <CAPXz4EO5poAP+8+TVWOzahJMa7Q9NGVs+6RuvV38u=YX_xyV+g@mail.gmail.com>
Date: Fri, 22 Nov 2024 11:33:01 -0700
From: Nicolas Bretz <bretznic@...il.com>
To: syzbot <syzbot+fe2a25dae02a207717a0@...kaller.appspotmail.com>
Cc: linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [ext4?] kernel BUG in ext4_write_inline_data (2)

#syz test

--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -3562,6 +3562,12 @@ extern int ext4_get_max_inline_size(struct inode *inode);
 extern int ext4_find_inline_data_nolock(struct inode *inode);
 extern int ext4_destroy_inline_data(handle_t *handle, struct inode *inode);

+static inline bool ext4_inline_possible(struct inode *inode,
+ loff_t pos, unsigned int len)
+{
+ return pos + len <= ext4_get_max_inline_size(inode);
+}
+
 int ext4_readpage_inline(struct inode *inode, struct folio *folio);
 extern int ext4_try_to_write_inline_data(struct address_space *mapping,
  struct inode *inode,
--- a/fs/ext4/inline.c
+++ b/fs/ext4/inline.c
@@ -668,7 +668,7 @@ int ext4_try_to_write_inline_data(struct
address_space *mapping,
  struct folio *folio;
  struct ext4_iloc iloc;

- if (pos + len > ext4_get_max_inline_size(inode))
+ if (!ext4_inline_possible(inode, pos, len))
  goto convert;

  ret = ext4_get_inode_loc(inode, &iloc);
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3061,7 +3061,8 @@ static int ext4_da_write_end(struct file *file,

  if (write_mode != CONVERT_INLINE_DATA &&
      ext4_test_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA) &&
-     ext4_has_inline_data(inode))
+     ext4_has_inline_data(inode) &&
+     ext4_inline_possible(inode, pos, len))
  return ext4_write_inline_data_end(inode, pos, len, copied,
    folio);