ext4: add extra checks to ext4_xattr_block_get()
Add explicit checks in ext4_xattr_block_get() just in case the
e_value_offs and e_value_size fields in the the xattr block are
corrupted in memory after the buffer_verified bit is set on the xattr
block.
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org
diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c
index 6304e81..499cb4b 100644
--- a/fs/ext4/xattr.c
+++ b/fs/ext4/xattr.c
@@ -197,7 +197,7 @@
while (!IS_LAST_ENTRY(entry)) {
u32 size = le32_to_cpu(entry->e_value_size);
- if (size > INT_MAX)
+ if (size > EXT4_XATTR_SIZE_MAX)
return -EFSCORRUPTED;
if (size != 0 && entry->e_value_inum == 0) {
@@ -540,8 +540,10 @@
if (error)
goto cleanup;
size = le32_to_cpu(entry->e_value_size);
+ error = -ERANGE;
+ if (unlikely(size > EXT4_XATTR_SIZE_MAX))
+ goto cleanup;
if (buffer) {
- error = -ERANGE;
if (size > buffer_size)
goto cleanup;
if (entry->e_value_inum) {
@@ -550,8 +552,12 @@
if (error)
goto cleanup;
} else {
- memcpy(buffer, bh->b_data +
- le16_to_cpu(entry->e_value_offs), size);
+ u16 offset = le16_to_cpu(entry->e_value_offs);
+ void *p = bh->b_data + offset;
+
+ if (unlikely(p + size > end))
+ goto cleanup;
+ memcpy(buffer, p, size);
}
}
error = size;
@@ -589,8 +595,10 @@
if (error)
goto cleanup;
size = le32_to_cpu(entry->e_value_size);
+ error = -ERANGE;
+ if (unlikely(size > EXT4_XATTR_SIZE_MAX))
+ goto cleanup;
if (buffer) {
- error = -ERANGE;
if (size > buffer_size)
goto cleanup;
if (entry->e_value_inum) {
@@ -599,8 +607,12 @@
if (error)
goto cleanup;
} else {
- memcpy(buffer, (void *)IFIRST(header) +
- le16_to_cpu(entry->e_value_offs), size);
+ u16 offset = le16_to_cpu(entry->e_value_offs);
+ void *p = (void *)IFIRST(header) + offset;
+
+ if (unlikely(p + size > end))
+ goto cleanup;
+ memcpy(buffer, p, size);
}
}
error = size;