f2fs: check memory boundary by insane namelen

PATCH In review Jaegeuk Kim 4 participants 5 messages Nov 15, 2018 – Nov 26, 2018 F2FS file system

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Jaegeuk Kim

author maintainer

2018-11-15 07:50 UTC #0 lore raw

PATCH 1/1 f2fs: check memory boundary by insane namelen

If namelen is corrupted to have very long value, fill_dentries can copy wrong memory area.

Signed-off-by Jaegeuk Kim <[email protected]>

---
 fs/f2fs/dir.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

fs/f2fs/dir.c +11 -1

index bacc667950b6..c0c845da12fa 100644
@@ -808,6 +808,17 @@ int f2fs_fill_dentries(struct dir_context *ctx, struct f2fs_dentry_ptr *d,
 		de_name.name = d->filename[bit_pos];
 		de_name.len = le16_to_cpu(de->name_len);
 
+		/* check memory boundary before moving forward */
+		bit_pos += GET_DENTRY_SLOTS(le16_to_cpu(de->name_len));
+		if (unlikely(bit_pos > d->max)) {
+			f2fs_msg(sbi->sb, KERN_WARNING,
+				"%s: corrupted namelen=%d, run fsck to fix.",
+				__func__, le16_to_cpu(de->name_len));
+			set_sbi_flag(sbi, SBI_NEED_FSCK);
+			err = -EINVAL;
+			goto out;
+		}
+
 		if (f2fs_encrypted_inode(d->inode)) {
 			int save_len = fstr->len;

@@ -830,7 +841,6 @@ int f2fs_fill_dentries(struct dir_context *ctx, struct f2fs_dentry_ptr *d,
 		if (readdir_ra)
 			f2fs_ra_node_page(sbi, le32_to_cpu(de->ino));
 
-		bit_pos += GET_DENTRY_SLOTS(le16_to_cpu(de->name_len));
 		ctx->pos = start_pos + bit_pos;
 	}
 out:

Signature · 1 line

2.19.0.605.g01d371f741-goog

Chao Yu

maintainer Reviewed-by on v1 1/1

2018-11-17 02:27 UTC #1 lore raw

Quoted 4 lines · Jaegeuk Kim

If namelen is corrupted to have very long value, fill_dentries can copy wrong memory area.
Signed-off-by Jaegeuk Kim <[email protected]>

Reviewed-by Chao Yu <[email protected]>

Thanks,

Sheng Yong

2018-11-23 12:11 UTC #2 lore raw

In reply to Jaegeuk Kim

Hi, Jaegeuk and Chao,

Quoted 3 lines · Jaegeuk Kim

If namelen is corrupted to have very long value, fill_dentries can copy wrong memory area.

Is there any scenario that could hit this corruption? Or this is triggered by fuzzing injection?

thanks,
Sheng Yong

Quoted 36 lines

Signed-off-by Jaegeuk Kim <[email protected]>

---
  fs/f2fs/dir.c | 12 +++++++++++-
  1 file changed, 11 insertions(+), 1 deletion(-)

fs/f2fs/dir.c +11 -1

index bacc667950b6..c0c845da12fa 100644
@@ -808,6 +808,17 @@ int f2fs_fill_dentries(struct dir_context *ctx, struct f2fs_dentry_ptr *d,
  		de_name.name = d->filename[bit_pos];
  		de_name.len = le16_to_cpu(de->name_len);
 
+		/* check memory boundary before moving forward */
+		bit_pos += GET_DENTRY_SLOTS(le16_to_cpu(de->name_len));
+		if (unlikely(bit_pos > d->max)) {
+			f2fs_msg(sbi->sb, KERN_WARNING,
+				"%s: corrupted namelen=%d, run fsck to fix.",
+				__func__, le16_to_cpu(de->name_len));
+			set_sbi_flag(sbi, SBI_NEED_FSCK);
+			err = -EINVAL;
+			goto out;
+		}
+
  		if (f2fs_encrypted_inode(d->inode)) {
  			int save_len = fstr->len;

@@ -830,7 +841,6 @@ int f2fs_fill_dentries(struct dir_context *ctx, struct f2fs_dentry_ptr *d,
  		if (readdir_ra)
  			f2fs_ra_node_page(sbi, le32_to_cpu(de->ino));
 
-		bit_pos += GET_DENTRY_SLOTS(le16_to_cpu(de->name_len));
  		ctx->pos = start_pos + bit_pos;
  	}
  out:

Chao Yu

2018-11-24 09:59 UTC #3 lore raw

Hi Sheng,

Quoted 7 lines · Sheng Yong

Hi, Jaegeuk and Chao,
Quoted 3 lines · Jaegeuk Kim
If namelen is corrupted to have very long value, fill_dentries can copy wrong memory area.
Is there any scenario that could hit this corruption? Or this is triggered

I didn't see such issue in my test, I guess it may be caused by fuzzing test.

Thanks,

Quoted 50 lines

by fuzzing injection?

thanks,
Sheng Yong

Quoted 29 lines

Signed-off-by Jaegeuk Kim <[email protected]>

---
  fs/f2fs/dir.c | 12 +++++++++++-
  1 file changed, 11 insertions(+), 1 deletion(-)

fs/f2fs/dir.c +11 -0

index bacc667950b6..c0c845da12fa 100644
@@ -808,6 +808,17 @@ int f2fs_fill_dentries(struct dir_context *ctx, struct f2fs_dentry_ptr *d,
  		de_name.name = d->filename[bit_pos];
  		de_name.len = le16_to_cpu(de->name_len);
 
+		/* check memory boundary before moving forward */
+		bit_pos += GET_DENTRY_SLOTS(le16_to_cpu(de->name_len));
+		if (unlikely(bit_pos > d->max)) {
+			f2fs_msg(sbi->sb, KERN_WARNING,
+				"%s: corrupted namelen=%d, run fsck to fix.",
+				__func__, le16_to_cpu(de->name_len));
+			set_sbi_flag(sbi, SBI_NEED_FSCK);
+			err = -EINVAL;
+			goto out;
+		}
+
  		if (f2fs_encrypted_inode(d->inode)) {
  			int save_len = fstr->len;

fs/f2fs/dir.c int f2fs_fill_dentries(struct dir_context *ctx, struct f2fs_dentry_ptr *d, · line 846

Quoted 7 lines

fs/f2fs/dir.c +0 -1

@@ -830,7 +841,6 @@ int f2fs_fill_dentries(struct dir_context *ctx, struct f2fs_dentry_ptr *d,
  		if (readdir_ra)
  			f2fs_ra_node_page(sbi, le32_to_cpu(de->ino));
 
-		bit_pos += GET_DENTRY_SLOTS(le16_to_cpu(de->name_len));
  		ctx->pos = start_pos + bit_pos;
  	}
  out:

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Jaegeuk Kim

author maintainer

2018-11-26 23:25 UTC #4 lore raw

In reply to Sheng Yong

Quoted 8 lines · Sheng Yong

Hi, Jaegeuk and Chao,
Quoted 3 lines · Jaegeuk Kim
If namelen is corrupted to have very long value, fill_dentries can copy wrong memory area.
Is there any scenario that could hit this corruption? Or this is triggered by fuzzing injection?

Hi Sheng,

It's from a fuzzing test.

Thanks,

Quoted 37 lines

thanks,
Sheng Yong

Quoted 33 lines

Signed-off-by Jaegeuk Kim <[email protected]>

---
  fs/f2fs/dir.c | 12 +++++++++++-
  1 file changed, 11 insertions(+), 1 deletion(-)

fs/f2fs/dir.c +11 -1

index bacc667950b6..c0c845da12fa 100644
@@ -808,6 +808,17 @@ int f2fs_fill_dentries(struct dir_context *ctx, struct f2fs_dentry_ptr *d,
  		de_name.name = d->filename[bit_pos];
  		de_name.len = le16_to_cpu(de->name_len);
+		/* check memory boundary before moving forward */
+		bit_pos += GET_DENTRY_SLOTS(le16_to_cpu(de->name_len));
+		if (unlikely(bit_pos > d->max)) {
+			f2fs_msg(sbi->sb, KERN_WARNING,
+				"%s: corrupted namelen=%d, run fsck to fix.",
+				__func__, le16_to_cpu(de->name_len));
+			set_sbi_flag(sbi, SBI_NEED_FSCK);
+			err = -EINVAL;
+			goto out;
+		}
+
  		if (f2fs_encrypted_inode(d->inode)) {
  			int save_len = fstr->len;

@@ -830,7 +841,6 @@ int f2fs_fill_dentries(struct dir_context *ctx, struct f2fs_dentry_ptr *d,
  		if (readdir_ra)
  			f2fs_ra_node_page(sbi, le32_to_cpu(de->ino));
-		bit_pos += GET_DENTRY_SLOTS(le16_to_cpu(de->name_len));
  		ctx->pos = start_pos + bit_pos;
  	}
  out: