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From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Josh Poimboeuf <jpoimboe@redhat.com>,
	Wang ShaoBo <bobo.shaobowang@huawei.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Sasha Levin <sashal@kernel.org>
Subject: [PATCH AUTOSEL 5.7 18/25] x86/unwind/orc: Fix ORC for newly forked tasks
Date: Mon, 27 Jul 2020 19:23:38 -0400	[thread overview]
Message-ID: <20200727232345.717432-18-sashal@kernel.org> (raw)
In-Reply-To: <20200727232345.717432-1-sashal@kernel.org>

From: Josh Poimboeuf <jpoimboe@redhat.com>

[ Upstream commit 372a8eaa05998cd45b3417d0e0ffd3a70978211a ]

The ORC unwinder fails to unwind newly forked tasks which haven't yet
run on the CPU.  It correctly reads the 'ret_from_fork' instruction
pointer from the stack, but it incorrectly interprets that value as a
call stack address rather than a "signal" one, so the address gets
incorrectly decremented in the call to orc_find(), resulting in bad ORC
data.

Fix it by forcing 'ret_from_fork' frames to be signal frames.

Reported-by: Wang ShaoBo <bobo.shaobowang@huawei.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Wang ShaoBo <bobo.shaobowang@huawei.com>
Link: https://lkml.kernel.org/r/f91a8778dde8aae7f71884b5df2b16d552040441.1594994374.git.jpoimboe@redhat.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 arch/x86/kernel/unwind_orc.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/unwind_orc.c b/arch/x86/kernel/unwind_orc.c
index 7f969b2d240fd..ec88bbe08a328 100644
--- a/arch/x86/kernel/unwind_orc.c
+++ b/arch/x86/kernel/unwind_orc.c
@@ -440,8 +440,11 @@ bool unwind_next_frame(struct unwind_state *state)
 	/*
 	 * Find the orc_entry associated with the text address.
 	 *
-	 * Decrement call return addresses by one so they work for sibling
-	 * calls and calls to noreturn functions.
+	 * For a call frame (as opposed to a signal frame), state->ip points to
+	 * the instruction after the call.  That instruction's stack layout
+	 * could be different from the call instruction's layout, for example
+	 * if the call was to a noreturn function.  So get the ORC data for the
+	 * call instruction itself.
 	 */
 	orc = orc_find(state->signal ? state->ip : state->ip - 1);
 	if (!orc) {
@@ -662,6 +665,7 @@ void __unwind_start(struct unwind_state *state, struct task_struct *task,
 		state->sp = task->thread.sp;
 		state->bp = READ_ONCE_NOCHECK(frame->bp);
 		state->ip = READ_ONCE_NOCHECK(frame->ret_addr);
+		state->signal = (void *)state->ip == ret_from_fork;
 	}
 
 	if (get_stack_info((unsigned long *)state->sp, state->task,
-- 
2.25.1


  parent reply	other threads:[~2020-07-27 23:29 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-27 23:23 [PATCH AUTOSEL 5.7 01/25] mt76: mt7615: fix lmac queue debugsfs entry Sasha Levin
2020-07-27 23:23 ` [PATCH AUTOSEL 5.7 02/25] iwlwifi: fix crash in iwl_dbg_tlv_alloc_trigger Sasha Levin
2020-07-27 23:23 ` [PATCH AUTOSEL 5.7 03/25] usb: hso: Fix debug compile warning on sparc32 Sasha Levin
2020-07-27 23:23 ` [PATCH AUTOSEL 5.7 04/25] selftests: fib_nexthop_multiprefix: fix cleanup() netns deletion Sasha Levin
2020-07-27 23:23 ` [PATCH AUTOSEL 5.7 05/25] qed: Disable "MFW indication via attention" SPAM every 5 minutes Sasha Levin
2020-07-27 23:23 ` [PATCH AUTOSEL 5.7 06/25] selftests: net: ip_defrag: modprobe missing nf_defrag_ipv6 support Sasha Levin
2020-07-27 23:23 ` [PATCH AUTOSEL 5.7 07/25] io_uring: always allow drain/link/hardlink/async sqe flags Sasha Levin
2020-07-27 23:23 ` [PATCH AUTOSEL 5.7 08/25] habanalabs: prevent possible out-of-bounds array access Sasha Levin
2020-07-27 23:23 ` [PATCH AUTOSEL 5.7 09/25] nfc: s3fwrn5: add missing release on skb in s3fwrn5_recv_frame Sasha Levin
2020-07-27 23:23 ` [PATCH AUTOSEL 5.7 10/25] scsi: core: Run queue in case of I/O resource contention failure Sasha Levin
2020-07-27 23:23 ` [PATCH AUTOSEL 5.7 11/25] riscv: kasan: use local_tlb_flush_all() to avoid uninitialized __sbi_rfence Sasha Levin
2020-07-27 23:23 ` [PATCH AUTOSEL 5.7 12/25] parisc: add support for cmpxchg on u8 pointers Sasha Levin
2020-07-27 23:23 ` [PATCH AUTOSEL 5.7 13/25] net: ethernet: ravb: exit if re-initialization fails in tx timeout Sasha Levin
2020-07-27 23:23 ` [PATCH AUTOSEL 5.7 14/25] selftest: txtimestamp: fix net ns entry logic Sasha Levin
2020-07-27 23:23 ` [PATCH AUTOSEL 5.7 15/25] drivers/net/wan/x25_asy: Fix to make it work Sasha Levin
2020-07-27 23:23 ` [PATCH AUTOSEL 5.7 16/25] Revert "i2c: cadence: Fix the hold bit setting" Sasha Levin
2020-07-27 23:23 ` [PATCH AUTOSEL 5.7 17/25] i2c: cadence: Clear HOLD bit at correct time in Rx path Sasha Levin
2020-07-27 23:23 ` Sasha Levin [this message]
2020-07-27 23:23 ` [PATCH AUTOSEL 5.7 19/25] x86/stacktrace: Fix reliable check for empty user task stacks Sasha Levin
2020-07-27 23:23 ` [PATCH AUTOSEL 5.7 20/25] cxgb4: add missing release on skb in uld_send() Sasha Levin
2020-07-27 23:23 ` [PATCH AUTOSEL 5.7 21/25] io_uring: missed req_init_async() for IOSQE_ASYNC Sasha Levin
2020-07-27 23:23 ` [PATCH AUTOSEL 5.7 22/25] xen-netfront: fix potential deadlock in xennet_remove() Sasha Levin
2020-07-27 23:23 ` [PATCH AUTOSEL 5.7 23/25] RISC-V: Set maximum number of mapped pages correctly Sasha Levin
2020-07-27 23:23 ` [PATCH AUTOSEL 5.7 24/25] drivers/net/wan: lapb: Corrected the usage of skb_cow Sasha Levin
2020-07-27 23:23 ` [PATCH AUTOSEL 5.7 25/25] riscv: Parse all memory blocks to remove unusable memory Sasha Levin

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