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| author | Theodore Ts'o <tytso@mit.edu> | 2018-09-01 12:45:04 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-09-29 02:56:00 -0700 |
| commit | a4cb1bf267a6db789655f05810dfb328e130a14c (patch) | |
| tree | a88959e357e07c1f3923074accda9499f87fb787 /fs | |
| parent | 976eeff67a3ad52c8337e3e10d10ae0a93e7f1ec (diff) | |
| download | linux-stable-a4cb1bf267a6db789655f05810dfb328e130a14c.tar.gz linux-stable-a4cb1bf267a6db789655f05810dfb328e130a14c.tar.bz2 linux-stable-a4cb1bf267a6db789655f05810dfb328e130a14c.zip | |
ext4: avoid arithemetic overflow that can trigger a BUG
commit bcd8e91f98c156f4b1ebcfacae675f9cfd962441 upstream.
A maliciously crafted file system can cause an overflow when the
results of a 64-bit calculation is stored into a 32-bit length
parameter.
https://bugzilla.kernel.org/show_bug.cgi?id=200623
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reported-by: Wen Xu <wen.xu@gatech.edu>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/ext4/ext4.h | 3 | ||||
| -rw-r--r-- | fs/ext4/inode.c | 8 |
2 files changed, 9 insertions, 2 deletions
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index 7c7123f265c2..aa1ce53d0c87 100644 --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -675,6 +675,9 @@ enum { /* Max physical block we can address w/o extents */ #define EXT4_MAX_BLOCK_FILE_PHYS 0xFFFFFFFF +/* Max logical block we can support */ +#define EXT4_MAX_LOGICAL_BLOCK 0xFFFFFFFF + /* * Structure of an inode on the disk */ diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 4efe77286ecd..0f730a5eda67 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -3412,12 +3412,16 @@ static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length, { struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb); unsigned int blkbits = inode->i_blkbits; - unsigned long first_block = offset >> blkbits; - unsigned long last_block = (offset + length - 1) >> blkbits; + unsigned long first_block, last_block; struct ext4_map_blocks map; bool delalloc = false; int ret; + if ((offset >> blkbits) > EXT4_MAX_LOGICAL_BLOCK) + return -EINVAL; + first_block = offset >> blkbits; + last_block = min_t(loff_t, (offset + length - 1) >> blkbits, + EXT4_MAX_LOGICAL_BLOCK); if (flags & IOMAP_REPORT) { if (ext4_has_inline_data(inode)) { |