[PATCH] qedi: Fix crash while reading debugfs attribute.

From: Manish Rangankar <mrangankar@marvell.com>
To: <martin.petersen@oracle.com>
Cc: <GR-QLogic-Storage-Upstream@marvell.com>,
	<linux-scsi@vger.kernel.org>,
	Manish Rangankar <mrangankar@marvell.com>,
	Martin Hoyer <mhoyer@redhat.com>
Subject: [PATCH] qedi: Fix crash while reading debugfs attribute.
Date: Wed, 27 Mar 2024 14:41:00 +0530	[thread overview]
Message-ID: <20240327091100.14405-1-mrangankar@marvell.com> (raw)

BUG: unable to handle page fault for address: 00007f4801111000
PGD 8000000864df6067 P4D 8000000864df6067 PUD 864df7067 PMD 846028067 PTE 0
Oops: 0002 [#1] PREEMPT SMP PTI
CPU: 38 PID: 6417 Comm: cat Kdump: loaded Not tainted 6.4.0-150600.9-default #1 SLE15-SP6 6b4f1850a99c4e4121f832c3fb6a8cf64ec22338
Hardware name: HPE ProLiant DL380 Gen10/ProLiant DL380 Gen10, BIOS U30 06/15/2023
RIP: 0010:memcpy_orig+0xcd/0x130
Code: 08 4c 89 54 17 f0 4c 89 5c 17 f8 c3 cc cc cc cc 66 66 2e 0f 1f 84 00 00 00 00 00 66 90 83 fa 08 72 1b 4c 8b 06 4c 8b 4c 16 f8 <4c> 89 07 4c 89 4c 17 f8 c3 cc cc cc cc 66 0f 1f 44 00 00 83 fa 04
RSP: 0018:ffffb7a18c3ffc40 EFLAGS: 00010202
RAX: 00007f4801111000 RBX: 00007f4801111000 RCX: 000000000000000f
RDX: 000000000000000f RSI: ffffffffc0bfd7a0 RDI: 00007f4801111000
RBP: ffffffffc0bfd7a0 R08: 725f746f6e5f6f64 R09: 3d7265766f636572
R10: ffffb7a18c3ffd08 R11: 0000000000000000 R12: 00007f4881110fff
R13: 000000007fffffff R14: ffffb7a18c3ffca0 R15: ffffffffc0bfd7af
FS:  00007f480118a740(0000) GS:ffff98e38af00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f4801111000 CR3: 0000000864b8e001 CR4: 00000000007706e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
PKRU: 55555554
Call Trace:
 <TASK>
 ? __die_body+0x1a/0x60
 ? page_fault_oops+0x183/0x510
 ? exc_page_fault+0x69/0x150
 ? asm_exc_page_fault+0x22/0x30
 ? memcpy_orig+0xcd/0x130
 vsnprintf+0x102/0x4c0
 sprintf+0x51/0x80
 qedi_dbg_do_not_recover_cmd_read+0x2f/0x50 [qedi 6bcfdeeecdea037da47069eca2ba717c84a77324]
 full_proxy_read+0x50/0x80
 vfs_read+0xa5/0x2e0
 ? folio_add_new_anon_rmap+0x44/0xa0
 ? set_pte_at+0x15/0x30
 ? do_pte_missing+0x426/0x7f0
 ksys_read+0xa5/0xe0
 do_syscall_64+0x58/0x80
 ? __count_memcg_events+0x46/0x90
 ? count_memcg_event_mm+0x3d/0x60
 ? handle_mm_fault+0x196/0x2f0
 ? do_user_addr_fault+0x267/0x890
 ? exc_page_fault+0x69/0x150
 entry_SYSCALL_64_after_hwframe+0x72/0xdc
RIP: 0033:0x7f4800f20b4d

Reported-by: Martin Hoyer <mhoyer@redhat.com>
Signed-off-by: Manish Rangankar <mrangankar@marvell.com>
---
 drivers/scsi/qedi/qedi_debugfs.c | 12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/drivers/scsi/qedi/qedi_debugfs.c b/drivers/scsi/qedi/qedi_debugfs.c
index 8deb2001dc2f..37eed6a27816 100644
--- a/drivers/scsi/qedi/qedi_debugfs.c
+++ b/drivers/scsi/qedi/qedi_debugfs.c
@@ -120,15 +120,11 @@ static ssize_t
 qedi_dbg_do_not_recover_cmd_read(struct file *filp, char __user *buffer,
 				 size_t count, loff_t *ppos)
 {
-	size_t cnt = 0;
-
-	if (*ppos)
-		return 0;
+	char buf[64];
+	int len;
 
-	cnt = sprintf(buffer, "do_not_recover=%d\n", qedi_do_not_recover);
-	cnt = min_t(int, count, cnt - *ppos);
-	*ppos += cnt;
-	return cnt;
+	len = sprintf(buf, "do_not_recover=%d\n", qedi_do_not_recover);
+	return simple_read_from_buffer(buffer, count, ppos, buf, len);
 }
 
 static int
-- 
2.35.3

