[PATCH AUTOSEL 5.10 05/24] scsi: lpfc: Prevent lpfc_debugfs_lockstat_write() buffer overflow

Sasha Levin
2023-05-04T20:02:09Z

From: Justin Tee <justin.tee@broadcom.com>

[ Upstream commit c6087b82a9146826564a55c5ca0164cac40348f5 ]

A static code analysis tool flagged the possibility of buffer overflow when
using copy_from_user() for a debugfs entry.

Currently, it is possible that copy_from_user() copies more bytes than what
would fit in the mybuf char array. Add a min() restriction check between
sizeof(mybuf) - 1 and nbytes passed from the userspace buffer to protect
against buffer overflow.

Link: https://lore.kernel.org/r/20230301231626.9621-2-justintee8345@gmail.com
Signed-off-by: Justin Tee <justin.tee@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/scsi/lpfc/lpfc_debugfs.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/scsi/lpfc/lpfc_debugfs.c b/drivers/scsi/lpfc/lpfc_debugfs.c
index fbc76d69ea0b4..2b77cbbcdccb6 100644
--- a/drivers/scsi/lpfc/lpfc_debugfs.c
+++ b/drivers/scsi/lpfc/lpfc_debugfs.c
@@ -2159,10 +2159,13 @@ lpfc_debugfs_lockstat_write(struct file *file, const char __user *buf,
char mybuf[64];
char *pbuf;
int i;
+ size_t bsize;

memset(mybuf, 0, sizeof(mybuf));

- if (copy_from_user(mybuf, buf, nbytes))
+ bsize = min(nbytes, (sizeof(mybuf) - 1));
+
+ if (copy_from_user(mybuf, buf, bsize))
return -EFAULT;
pbuf = &mybuf[0];

@@ -2183,7 +2186,7 @@ lpfc_debugfs_lockstat_write(struct file *file, const char __user *buf,
qp->lock_conflict.wq_access = 0;
}
}
- return nbytes;
+ return bsize;
}
#endif

--
2.39.2