projects / thirdparty / kernel / stable-queue.git / blame
| Commit | Line | Data |
|---|---|---|
| 0f23eb5b GKH |
1 | From 54dd0e0a1b255f115f8647fc6fb93273251b01b9 Mon Sep 17 00:00:00 2001 |
| 2 | From: Theodore Ts'o <tytso@mit.edu> | |
| 3 | Date: Fri, 30 Mar 2018 20:04:11 -0400 | |
| 4 | Subject: ext4: add extra checks to ext4_xattr_block_get() | |
| 5 | ||
| 6 | From: Theodore Ts'o <tytso@mit.edu> | |
| 7 | ||
| 8 | commit 54dd0e0a1b255f115f8647fc6fb93273251b01b9 upstream. | |
| 9 | ||
| 10 | Add explicit checks in ext4_xattr_block_get() just in case the | |
| 11 | e_value_offs and e_value_size fields in the the xattr block are | |
| 12 | corrupted in memory after the buffer_verified bit is set on the xattr | |
| 13 | block. | |
| 14 | ||
| 15 | Signed-off-by: Theodore Ts'o <tytso@mit.edu> | |
| 16 | Cc: stable@kernel.org | |
| 17 | Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> | |
| 18 | ||
| 19 | --- | |
| 20 | fs/ext4/xattr.c | 26 +++++++++++++++++++------- | |
| 21 | fs/ext4/xattr.h | 11 +++++++++++ | |
| 22 | 2 files changed, 30 insertions(+), 7 deletions(-) | |
| 23 | ||
| 24 | --- a/fs/ext4/xattr.c | |
| 25 | +++ b/fs/ext4/xattr.c | |
| 26 | @@ -197,7 +197,7 @@ ext4_xattr_check_entries(struct ext4_xat | |
| 27 | while (!IS_LAST_ENTRY(entry)) { | |
| 28 | u32 size = le32_to_cpu(entry->e_value_size); | |
| 29 | ||
| 30 | - if (size > INT_MAX) | |
| 31 | + if (size > EXT4_XATTR_SIZE_MAX) | |
| 32 | return -EFSCORRUPTED; | |
| 33 | ||
| 34 | if (size != 0 && entry->e_value_inum == 0) { | |
| 35 | @@ -540,8 +540,10 @@ ext4_xattr_block_get(struct inode *inode | |
| 36 | if (error) | |
| 37 | goto cleanup; | |
| 38 | size = le32_to_cpu(entry->e_value_size); | |
| 39 | + error = -ERANGE; | |
| 40 | + if (unlikely(size > EXT4_XATTR_SIZE_MAX)) | |
| 41 | + goto cleanup; | |
| 42 | if (buffer) { | |
| 43 | - error = -ERANGE; | |
| 44 | if (size > buffer_size) | |
| 45 | goto cleanup; | |
| 46 | if (entry->e_value_inum) { | |
| 47 | @@ -550,8 +552,12 @@ ext4_xattr_block_get(struct inode *inode | |
| 48 | if (error) | |
| 49 | goto cleanup; | |
| 50 | } else { | |
| 51 | - memcpy(buffer, bh->b_data + | |
| 52 | - le16_to_cpu(entry->e_value_offs), size); | |
| 53 | + u16 offset = le16_to_cpu(entry->e_value_offs); | |
| 54 | + void *p = bh->b_data + offset; | |
| 55 | + | |
| 56 | + if (unlikely(p + size > end)) | |
| 57 | + goto cleanup; | |
| 58 | + memcpy(buffer, p, size); | |
| 59 | } | |
| 60 | } | |
| 61 | error = size; | |
| 62 | @@ -589,8 +595,10 @@ ext4_xattr_ibody_get(struct inode *inode | |
| 63 | if (error) | |
| 64 | goto cleanup; | |
| 65 | size = le32_to_cpu(entry->e_value_size); | |
| 66 | + error = -ERANGE; | |
| 67 | + if (unlikely(size > EXT4_XATTR_SIZE_MAX)) | |
| 68 | + goto cleanup; | |
| 69 | if (buffer) { | |
| 70 | - error = -ERANGE; | |
| 71 | if (size > buffer_size) | |
| 72 | goto cleanup; | |
| 73 | if (entry->e_value_inum) { | |
| 74 | @@ -599,8 +607,12 @@ ext4_xattr_ibody_get(struct inode *inode | |
| 75 | if (error) | |
| 76 | goto cleanup; | |
| 77 | } else { | |
| 78 | - memcpy(buffer, (void *)IFIRST(header) + | |
| 79 | - le16_to_cpu(entry->e_value_offs), size); | |
| 80 | + u16 offset = le16_to_cpu(entry->e_value_offs); | |
| 81 | + void *p = (void *)IFIRST(header) + offset; | |
| 82 | + | |
| 83 | + if (unlikely(p + size > end)) | |
| 84 | + goto cleanup; | |
| 85 | + memcpy(buffer, p, size); | |
| 86 | } | |
| 87 | } | |
| 88 | error = size; | |
| 89 | --- a/fs/ext4/xattr.h | |
| 90 | +++ b/fs/ext4/xattr.h | |
| 91 | @@ -71,6 +71,17 @@ struct ext4_xattr_entry { | |
| 92 | #define IFIRST(hdr) ((struct ext4_xattr_entry *)((hdr)+1)) | |
| 93 | ||
| 94 | /* | |
| 95 | + * XATTR_SIZE_MAX is currently 64k, but for the purposes of checking | |
| 96 | + * for file system consistency errors, we use a somewhat bigger value. | |
| 97 | + * This allows XATTR_SIZE_MAX to grow in the future, but by using this | |
| 98 | + * instead of INT_MAX for certain consistency checks, we don't need to | |
| 99 | + * worry about arithmetic overflows. (Actually XATTR_SIZE_MAX is | |
| 100 | + * defined in include/uapi/linux/limits.h, so changing it is going | |
| 101 | + * not going to be trivial....) | |
| 102 | + */ | |
| 103 | +#define EXT4_XATTR_SIZE_MAX (1 << 24) | |
| 104 | + | |
| 105 | +/* | |
| 106 | * The minimum size of EA value when you start storing it in an external inode | |
| 107 | * size of block - size of header - size of 1 entry - 4 null bytes | |
| 108 | */ |