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bcachefs: fix invalid free in dio write path

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turns out iterate_iovec() mutates __iov, we need to save our own copy

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Reported-by: Marcin Mirosław <marcin@mejor.pl>
This commit is contained in:
Kent Overstreet 2023-12-30 20:52:18 -05:00
parent fa014953f9
commit f2eb8434e4
1 changed files with 5 additions and 8 deletions
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13
fs/bcachefs/fs-io-direct.c
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@ -216,11 +216,11 @@ struct dio_write {
struct address_space *mapping;
struct bch_inode_info *inode;
struct mm_struct *mm;
const struct iovec *iov;
unsigned loop:1,
extending:1,
sync:1,
flush:1,
free_iov:1;
flush:1;
struct quota_res quota_res;
u64 written;
@ -312,12 +312,10 @@ static noinline int bch2_dio_write_copy_iov(struct dio_write *dio)
return -1;
if (dio->iter.nr_segs > ARRAY_SIZE(dio->inline_vecs)) {
iov = kmalloc_array(dio->iter.nr_segs, sizeof(*iov),
dio->iov = iov = kmalloc_array(dio->iter.nr_segs, sizeof(*iov),
GFP_KERNEL);
if (unlikely(!iov))
return -ENOMEM;
dio->free_iov = true;
}
memcpy(iov, dio->iter.__iov, dio->iter.nr_segs * sizeof(*iov));
@ -381,8 +379,7 @@ static __always_inline long bch2_dio_write_done(struct dio_write *dio)
bch2_pagecache_block_put(inode);
if (dio->free_iov)
kfree(dio->iter.__iov);
kfree(dio->iov);
ret = dio->op.error ?: ((long) dio->written << 9);
bio_put(&dio->op.wbio.bio);
@ -626,11 +623,11 @@ ssize_t bch2_direct_write(struct kiocb *req, struct iov_iter *iter)
dio->mapping = mapping;
dio->inode = inode;
dio->mm = current->mm;
dio->iov = NULL;
dio->loop = false;
dio->extending = extending;
dio->sync = is_sync_kiocb(req) || extending;
dio->flush = iocb_is_dsync(req) && !c->opts.journal_flush_disabled;
dio->free_iov = false;
dio->quota_res.sectors = 0;
dio->written = 0;
dio->iter = *iter;