From f6edc45e21c35f9e0124f7ac8b2d8eb7f551cc3b Mon Sep 17 00:00:00 2001 From: David Sterba Date: Mon, 16 Apr 2018 21:10:14 +0200 Subject: [PATCH] btrfs: fix unaligned access in readdir MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit commit 92d32170847bfff2dd08af2c016085779f2fd2a1 upstream. 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 Reviewed-by: Liu Bo Signed-off-by: David Sterba Signed-off-by: Greg Kroah-Hartman --- fs/btrfs/inode.c | 20 ++++++++++++-------- 1 file changed, 12 insertions(+), 8 deletions(-) diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index dfa360d18ae2..768661aa885c 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -42,6 +42,7 @@ #include #include #include +#include #include "ctree.h" #include "disk-io.h" #include "transaction.h" @@ -5980,11 +5981,13 @@ 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; @@ -6078,14 +6081,15 @@ 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; -- 2.20.1