diff options
| author | Sujit Reddy Thumma <sthumma@codeaurora.org> | 2014-12-09 20:44:41 +0200 |
|---|---|---|
| committer | Subhash Jadavani <subhashj@codeaurora.org> | 2016-05-31 15:26:00 -0700 |
| commit | c75b73aff388cd297fa0e85f89eb575acf16873c (patch) | |
| tree | 7903f53fb7c65a13455f06a0e47b780998dad7a0 | |
| parent | 248d1fcebed5f136804f86cff4501ed0461e84ee (diff) | |
mmc: core: Fix null pointer dereference due to illegal mmc request
Fix a race condition that can lead to null pointer dereference
while the MMC transfers are going on.
1) mmc_request_done() -> mmc_wait_for_data_done ->
step1: update is_done_rcv
step2: wake_up sleeping thread (mmcqd) waiting for is_done_rcv
2) mmcqd -> mmc_wait_for_data_req_done
step4: wait for is_done_rcv or is_new_req
step5: is_new_req set from block layer context and mmcqd
is woken up
step6: let's say step1 is done, so complete the current request
step7: fetch new request and issue to host layer
step8: fetch one more request and wait for previous request to
complete
In the above execution contexts, if step4-step8 happens between step1 and
step2 a null pointer dereference is observed -
[ 29.483302] Unable to handle kernel NULL pointer dereference
at virtual address 00000488
[ 29.490366] pgd = c0004000
[ 29.493054] [00000488] *pgd=00000000
[ 29.518937] PC is at do_raw_spin_lock+0x8/0x13c
[ 29.523445] LR is at _raw_spin_lock_irqsave+0x20/0x28
[ 30.108789] [<c0339cd4>] (do_raw_spin_lock+0x8/0x13c) from
[ 30.118418] [<c095d178>] (_raw_spin_lock_irqsave+0x20/0x28) from
[ 30.127445] [<c0142ef4>] (__wake_up+0x20/0x50) from
[ 30.136124] [<c0663f70>] (mmc_request_done+0x30c/0x368) from
[ 30.145932] [<c067bd98>] (sdhci_tasklet_finish+0x130/0x13c) from
Change-Id: I9a21431b5fd9bb9bbcb5c18a9895096fe845e64b
Signed-off-by: Sujit Reddy Thumma <sthumma@codeaurora.org>
[merez@codeaurora.org: fixed conflicts due to missing stop transmission]
Signed-off-by: Maya Erez <merez@codeaurora.org>
[subhashj@codeaurora.org: fixed trivial merge conflicts]
Signed-off-by: Subhash Jadavani <subhashj@codeaurora.org>
| -rw-r--r-- | drivers/mmc/core/core.c | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c index 188ace67504b..9e60bd2d021c 100644 --- a/drivers/mmc/core/core.c +++ b/drivers/mmc/core/core.c @@ -463,10 +463,13 @@ EXPORT_SYMBOL(mmc_start_bkops); */ static void mmc_wait_data_done(struct mmc_request *mrq) { + unsigned long flags; struct mmc_context_info *context_info = &mrq->host->context_info; + spin_lock_irqsave(&context_info->lock, flags); context_info->is_done_rcv = true; wake_up_interruptible(&context_info->wait); + spin_unlock_irqrestore(&context_info->lock, flags); } static void mmc_wait_done(struct mmc_request *mrq) @@ -532,6 +535,7 @@ static int mmc_wait_for_data_req_done(struct mmc_host *host, struct mmc_command *cmd; struct mmc_context_info *context_info = &host->context_info; int err; + bool is_done_rcv = false; unsigned long flags; while (1) { @@ -539,9 +543,10 @@ static int mmc_wait_for_data_req_done(struct mmc_host *host, (context_info->is_done_rcv || context_info->is_new_req)); spin_lock_irqsave(&context_info->lock, flags); + is_done_rcv = context_info->is_done_rcv; context_info->is_waiting_last_req = false; spin_unlock_irqrestore(&context_info->lock, flags); - if (context_info->is_done_rcv) { + if (is_done_rcv) { context_info->is_done_rcv = false; context_info->is_new_req = false; cmd = mrq->cmd; |