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| author | David Sterba <dsterba@suse.com> | 2018-04-16 21:10:14 +0200 |
|---|---|---|
| committer | David Sterba <dsterba@suse.com> | 2018-04-19 00:35:08 +0200 |
| commit | 92d32170847bfff2dd08af2c016085779f2fd2a1 (patch) | |
| tree | a86cbb655e5a787084da9c57b96de6bdcfd93b2e /fs | |
| parent | 336a8bb8e36a273a802a54b2e673c777c9c62fb1 (diff) | |
| download | linux-92d32170847bfff2dd08af2c016085779f2fd2a1.tar.gz linux-92d32170847bfff2dd08af2c016085779f2fd2a1.tar.bz2 linux-92d32170847bfff2dd08af2c016085779f2fd2a1.zip | |
btrfs: fix unaligned access in readdir
The last update to readdir introduced a temporary buffer to store the
emitted readdir data, but as there are file names of variable length,
there's a lot of unaligned access.
This was observed on a sparc64 machine:
Kernel unaligned access at TPC[102f3080] btrfs_real_readdir+0x51c/0x718 [btrfs]
Fixes: 23b5ec74943 ("btrfs: fix readdir deadlock with pagefault")
CC: stable@vger.kernel.org # 4.14+
Reported-and-tested-by: René Rebe <rene@exactcode.com>
Reviewed-by: Liu Bo <bo.liu@linux.alibaba.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/btrfs/inode.c | 20 |
1 files changed, 12 insertions, 8 deletions
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index e064c49c9a9a..d241285a0d2a 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -31,6 +31,7 @@ #include <linux/uio.h> #include <linux/magic.h> #include <linux/iversion.h> +#include <asm/unaligned.h> #include "ctree.h" #include "disk-io.h" #include "transaction.h" @@ -5905,11 +5906,13 @@ static int btrfs_filldir(void *addr, int entries, struct dir_context *ctx) struct dir_entry *entry = addr; char *name = (char *)(entry + 1); - ctx->pos = entry->offset; - if (!dir_emit(ctx, name, entry->name_len, entry->ino, - entry->type)) + ctx->pos = get_unaligned(&entry->offset); + if (!dir_emit(ctx, name, get_unaligned(&entry->name_len), + get_unaligned(&entry->ino), + get_unaligned(&entry->type))) return 1; - addr += sizeof(struct dir_entry) + entry->name_len; + addr += sizeof(struct dir_entry) + + get_unaligned(&entry->name_len); ctx->pos++; } return 0; @@ -5999,14 +6002,15 @@ again: } entry = addr; - entry->name_len = name_len; + put_unaligned(name_len, &entry->name_len); name_ptr = (char *)(entry + 1); read_extent_buffer(leaf, name_ptr, (unsigned long)(di + 1), name_len); - entry->type = btrfs_filetype_table[btrfs_dir_type(leaf, di)]; + put_unaligned(btrfs_filetype_table[btrfs_dir_type(leaf, di)], + &entry->type); btrfs_dir_item_key_to_cpu(leaf, di, &location); - entry->ino = location.objectid; - entry->offset = found_key.offset; + put_unaligned(location.objectid, &entry->ino); + put_unaligned(found_key.offset, &entry->offset); entries++; addr += sizeof(struct dir_entry) + name_len; total_len += sizeof(struct dir_entry) + name_len; |