projects / thirdparty / kernel / stable-queue.git / blame
| Commit | Line | Data |
|---|---|---|
| ec71c73b GKH |
1 | From 1c2d14212b15a60300a2d4f6364753e87394c521 Mon Sep 17 00:00:00 2001 |
| 2 | From: Jan Kara <jack@suse.cz> | |
| 3 | Date: Tue, 29 Jan 2019 17:17:24 +0100 | |
| 4 | Subject: ext2: Fix underflow in ext2_max_size() | |
| 5 | ||
| 6 | From: Jan Kara <jack@suse.cz> | |
| 7 | ||
| 8 | commit 1c2d14212b15a60300a2d4f6364753e87394c521 upstream. | |
| 9 | ||
| 10 | When ext2 filesystem is created with 64k block size, ext2_max_size() | |
| 11 | will return value less than 0. Also, we cannot write any file in this fs | |
| 12 | since the sb->maxbytes is less than 0. The core of the problem is that | |
| 13 | the size of block index tree for such large block size is more than | |
| 14 | i_blocks can carry. So fix the computation to count with this | |
| 15 | possibility. | |
| 16 | ||
| 17 | File size limits computed with the new function for the full range of | |
| 18 | possible block sizes look like: | |
| 19 | ||
| 20 | bits file_size | |
| 21 | 10 17247252480 | |
| 22 | 11 275415851008 | |
| 23 | 12 2196873666560 | |
| 24 | 13 2197948973056 | |
| 25 | 14 2198486220800 | |
| 26 | 15 2198754754560 | |
| 27 | 16 2198888906752 | |
| 28 | ||
| 29 | CC: stable@vger.kernel.org | |
| 30 | Reported-by: yangerkun <yangerkun@huawei.com> | |
| 31 | Signed-off-by: Jan Kara <jack@suse.cz> | |
| 32 | Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> | |
| 33 | ||
| 34 | --- | |
| 35 | fs/ext2/super.c | 41 ++++++++++++++++++++++++++--------------- | |
| 36 | 1 file changed, 26 insertions(+), 15 deletions(-) | |
| 37 | ||
| 38 | --- a/fs/ext2/super.c | |
| 39 | +++ b/fs/ext2/super.c | |
| 40 | @@ -761,7 +761,8 @@ static loff_t ext2_max_size(int bits) | |
| 41 | { | |
| 42 | loff_t res = EXT2_NDIR_BLOCKS; | |
| 43 | int meta_blocks; | |
| 44 | - loff_t upper_limit; | |
| 45 | + unsigned int upper_limit; | |
| 46 | + unsigned int ppb = 1 << (bits-2); | |
| 47 | ||
| 48 | /* This is calculated to be the largest file size for a | |
| 49 | * dense, file such that the total number of | |
| 50 | @@ -775,24 +776,34 @@ static loff_t ext2_max_size(int bits) | |
| 51 | /* total blocks in file system block size */ | |
| 52 | upper_limit >>= (bits - 9); | |
| 53 | ||
| 54 | - | |
| 55 | - /* indirect blocks */ | |
| 56 | - meta_blocks = 1; | |
| 57 | - /* double indirect blocks */ | |
| 58 | - meta_blocks += 1 + (1LL << (bits-2)); | |
| 59 | - /* tripple indirect blocks */ | |
| 60 | - meta_blocks += 1 + (1LL << (bits-2)) + (1LL << (2*(bits-2))); | |
| 61 | - | |
| 62 | - upper_limit -= meta_blocks; | |
| 63 | - upper_limit <<= bits; | |
| 64 | - | |
| 65 | + /* Compute how many blocks we can address by block tree */ | |
| 66 | res += 1LL << (bits-2); | |
| 67 | res += 1LL << (2*(bits-2)); | |
| 68 | res += 1LL << (3*(bits-2)); | |
| 69 | + /* Does block tree limit file size? */ | |
| 70 | + if (res < upper_limit) | |
| 71 | + goto check_lfs; | |
| 72 | + | |
| 73 | + res = upper_limit; | |
| 74 | + /* How many metadata blocks are needed for addressing upper_limit? */ | |
| 75 | + upper_limit -= EXT2_NDIR_BLOCKS; | |
| 76 | + /* indirect blocks */ | |
| 77 | + meta_blocks = 1; | |
| 78 | + upper_limit -= ppb; | |
| 79 | + /* double indirect blocks */ | |
| 80 | + if (upper_limit < ppb * ppb) { | |
| 81 | + meta_blocks += 1 + DIV_ROUND_UP(upper_limit, ppb); | |
| 82 | + res -= meta_blocks; | |
| 83 | + goto check_lfs; | |
| 84 | + } | |
| 85 | + meta_blocks += 1 + ppb; | |
| 86 | + upper_limit -= ppb * ppb; | |
| 87 | + /* tripple indirect blocks for the rest */ | |
| 88 | + meta_blocks += 1 + DIV_ROUND_UP(upper_limit, ppb) + | |
| 89 | + DIV_ROUND_UP(upper_limit, ppb*ppb); | |
| 90 | + res -= meta_blocks; | |
| 91 | +check_lfs: | |
| 92 | res <<= bits; | |
| 93 | - if (res > upper_limit) | |
| 94 | - res = upper_limit; | |
| 95 | - | |
| 96 | if (res > MAX_LFS_FILESIZE) | |
| 97 | res = MAX_LFS_FILESIZE; | |
| 98 |