From 4cf6bb23ac29912ff0bbb2c1ecc6dae37a8056d7 Mon Sep 17 00:00:00 2001 From: Coly Li Date: Mon, 10 Jun 2019 06:13:34 +0800 Subject: bcache: fix stack corruption by PRECEDING_KEY() commit 31b90956b124240aa8c63250243ae1a53585c5e2 upstream. Recently people report bcache code compiled with gcc9 is broken, one of the buggy behavior I observe is that two adjacent 4KB I/Os should merge into one but they don't. Finally it turns out to be a stack corruption caused by macro PRECEDING_KEY(). See how PRECEDING_KEY() is defined in bset.h, 437 #define PRECEDING_KEY(_k) \ 438 ({ \ 439 struct bkey *_ret = NULL; \ 440 \ 441 if (KEY_INODE(_k) || KEY_OFFSET(_k)) { \ 442 _ret = &KEY(KEY_INODE(_k), KEY_OFFSET(_k), 0); \ 443 \ 444 if (!_ret->low) \ 445 _ret->high--; \ 446 _ret->low--; \ 447 } \ 448 \ 449 _ret; \ 450 }) At line 442, _ret points to address of a on-stack variable combined by KEY(), the life range of this on-stack variable is in line 442-446, once _ret is returned to bch_btree_insert_key(), the returned address points to an invalid stack address and this address is overwritten in the following called bch_btree_iter_init(). Then argument 'search' of bch_btree_iter_init() points to some address inside stackframe of bch_btree_iter_init(), exact address depends on how the compiler allocates stack space. Now the stack is corrupted. Fixes: 0eacac22034c ("bcache: PRECEDING_KEY()") Signed-off-by: Coly Li Reviewed-by: Rolf Fokkens Reviewed-by: Pierre JUHEN Tested-by: Shenghui Wang Tested-by: Pierre JUHEN Cc: Kent Overstreet Cc: Nix Cc: stable@vger.kernel.org Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman --- drivers/md/bcache/bset.h | 34 ++++++++++++++++++++-------------- 1 file changed, 20 insertions(+), 14 deletions(-) (limited to 'drivers/md/bcache/bset.h') diff --git a/drivers/md/bcache/bset.h b/drivers/md/bcache/bset.h index ae964624efb2..b935839ab79c 100644 --- a/drivers/md/bcache/bset.h +++ b/drivers/md/bcache/bset.h @@ -417,20 +417,26 @@ static inline bool bch_cut_back(const struct bkey *where, struct bkey *k) return __bch_cut_back(where, k); } -#define PRECEDING_KEY(_k) \ -({ \ - struct bkey *_ret = NULL; \ - \ - if (KEY_INODE(_k) || KEY_OFFSET(_k)) { \ - _ret = &KEY(KEY_INODE(_k), KEY_OFFSET(_k), 0); \ - \ - if (!_ret->low) \ - _ret->high--; \ - _ret->low--; \ - } \ - \ - _ret; \ -}) +/* + * Pointer '*preceding_key_p' points to a memory object to store preceding + * key of k. If the preceding key does not exist, set '*preceding_key_p' to + * NULL. So the caller of preceding_key() needs to take care of memory + * which '*preceding_key_p' pointed to before calling preceding_key(). + * Currently the only caller of preceding_key() is bch_btree_insert_key(), + * and it points to an on-stack variable, so the memory release is handled + * by stackframe itself. + */ +static inline void preceding_key(struct bkey *k, struct bkey **preceding_key_p) +{ + if (KEY_INODE(k) || KEY_OFFSET(k)) { + (**preceding_key_p) = KEY(KEY_INODE(k), KEY_OFFSET(k), 0); + if (!(*preceding_key_p)->low) + (*preceding_key_p)->high--; + (*preceding_key_p)->low--; + } else { + (*preceding_key_p) = NULL; + } +} static inline bool bch_ptr_invalid(struct btree_keys *b, const struct bkey *k) { -- cgit v1.2.3 From fdfb5da5884daab71c77a7ec324eb2f79efbaaf0 Mon Sep 17 00:00:00 2001 From: Coly Li Date: Sat, 1 Feb 2020 22:42:32 +0800 Subject: bcache: explicity type cast in bset_bkey_last() [ Upstream commit 7c02b0055f774ed9afb6e1c7724f33bf148ffdc0 ] In bset.h, macro bset_bkey_last() is defined as, bkey_idx((struct bkey *) (i)->d, (i)->keys) Parameter i can be variable type of data structure, the macro always works once the type of struct i has member 'd' and 'keys'. bset_bkey_last() is also used in macro csum_set() to calculate the checksum of a on-disk data structure. When csum_set() is used to calculate checksum of on-disk bcache super block, the parameter 'i' data type is struct cache_sb_disk. Inside struct cache_sb_disk (also in struct cache_sb) the member keys is __u16 type. But bkey_idx() expects unsigned int (a 32bit width), so there is problem when sending parameters via stack to call bkey_idx(). Sparse tool from Intel 0day kbuild system reports this incompatible problem. bkey_idx() is part of user space API, so the simplest fix is to cast the (i)->keys to unsigned int type in macro bset_bkey_last(). Reported-by: kbuild test robot Signed-off-by: Coly Li Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin --- drivers/md/bcache/bset.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'drivers/md/bcache/bset.h') diff --git a/drivers/md/bcache/bset.h b/drivers/md/bcache/bset.h index b935839ab79c..f483041eed98 100644 --- a/drivers/md/bcache/bset.h +++ b/drivers/md/bcache/bset.h @@ -380,7 +380,8 @@ void bch_btree_keys_stats(struct btree_keys *, struct bset_stats *); /* Bkey utility code */ -#define bset_bkey_last(i) bkey_idx((struct bkey *) (i)->d, (i)->keys) +#define bset_bkey_last(i) bkey_idx((struct bkey *) (i)->d, \ + (unsigned int)(i)->keys) static inline struct bkey *bset_bkey_idx(struct bset *i, unsigned idx) { -- cgit v1.2.3