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Message-Id: <20210413104242.31564-1-mail@anirudhrb.com>
Date: Tue, 13 Apr 2021 16:12:42 +0530
From: Anirudh Rayabharam <mail@...rudhrb.com>
To: Luis Chamberlain <mcgrof@...nel.org>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
"Rafael J. Wysocki" <rafael@...nel.org>,
Junyong Sun <sunjy516@...il.com>
Cc: Anirudh Rayabharam <mail@...rudhrb.com>,
syzbot+de271708674e2093097b@...kaller.appspotmail.com,
linux-kernel@...r.kernel.org
Subject: [PATCH v2] firmware_loader: fix use-after-free in firmware_fallback_sysfs
The use-after-free happens when a fw_priv object has been freed but
hasn't been removed from the pending list (pending_fw_head). The next
time fw_load_sysfs_fallback tries to insert into the list, it ends up
accessing the pending_list member of the previoiusly freed fw_priv.
In commit bcfbd3523f3c ("firmware: fix a double abort case with
fw_load_sysfs_fallback"), fw_load_abort() is skipped if
fw_sysfs_wait_timeout() returns -ENOENT. This causes the fw_priv to
not be removed from the pending list.
To fix this, delete the fw_priv from the pending list when retval
is -ENOENT instead of skipping the entire block.
Fixes: bcfbd3523f3c ("firmware: fix a double abort case with fw_load_sysfs_fallback")
Reported-by: syzbot+de271708674e2093097b@...kaller.appspotmail.com
Tested-by: syzbot+de271708674e2093097b@...kaller.appspotmail.com
Signed-off-by: Anirudh Rayabharam <mail@...rudhrb.com>
---
Changes in v2:
1. Fixed 1 error and 1 warning (in the commit message) reported by
checkpatch.pl. The error was regarding the format for referring to
another commit "commit <sha> ("oneline")". The warning was for line
longer than 75 chars.
---
drivers/base/firmware_loader/fallback.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/drivers/base/firmware_loader/fallback.c b/drivers/base/firmware_loader/fallback.c
index 91899d185e31..56ae4ab3199d 100644
--- a/drivers/base/firmware_loader/fallback.c
+++ b/drivers/base/firmware_loader/fallback.c
@@ -526,9 +526,14 @@ static int fw_load_sysfs_fallback(struct fw_sysfs *fw_sysfs, long timeout)
}
retval = fw_sysfs_wait_timeout(fw_priv, timeout);
- if (retval < 0 && retval != -ENOENT) {
+ if (retval < 0) {
mutex_lock(&fw_lock);
- fw_load_abort(fw_sysfs);
+
+ if (retval != -ENOENT)
+ fw_load_abort(fw_sysfs);
+ else
+ list_del_init(&fw_priv->pending_list);
+
mutex_unlock(&fw_lock);
}
--
2.26.2
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