From e84843489c15bf9d39eec3a9a95870f98a71ac24 Mon Sep 17 00:00:00 2001 From: Kent Overstreet Date: Thu, 26 Oct 2023 17:00:36 -0400 Subject: [PATCH] bcachefs: Fix a kasan splat in bch2_dev_add() This fixes a use after free - mi is dangling after the resize call. Additionally, resizing the device's member info section was useless - we were attempting to preallocate the space required before adding it to the filesystem superblock, but there's other sections that we should have been preallocating as well for that to work. Signed-off-by: Kent Overstreet --- fs/bcachefs/super.c | 12 ++---------- 1 file changed, 2 insertions(+), 10 deletions(-) diff --git a/fs/bcachefs/super.c b/fs/bcachefs/super.c index ce59018b27ac..835342b56003 100644 --- a/fs/bcachefs/super.c +++ b/fs/bcachefs/super.c @@ -1622,16 +1622,6 @@ int bch2_dev_add(struct bch_fs *c, const char *path) goto err_unlock; } - mi = bch2_sb_field_get(ca->disk_sb.sb, members_v2); - - if (!bch2_sb_field_resize(&ca->disk_sb, members_v2, - le32_to_cpu(mi->field.u64s) + - sizeof(dev_mi) / sizeof(u64))) { - ret = -BCH_ERR_ENOSPC_sb_members; - bch_err_msg(c, ret, "setting up new superblock"); - goto err_unlock; - } - if (dynamic_fault("bcachefs:add:no_slot")) goto no_slot; @@ -1645,6 +1635,8 @@ no_slot: have_slot: nr_devices = max_t(unsigned, dev_idx + 1, c->sb.nr_devices); + + mi = bch2_sb_field_get(c->disk_sb.sb, members_v2); u64s = DIV_ROUND_UP(sizeof(struct bch_sb_field_members_v2) + le16_to_cpu(mi->member_bytes) * nr_devices, sizeof(u64));