Messages in this thread Patch in this message | | | From | Anirudh Rayabharam <> | Subject | [PATCH v2] firmware_loader: fix use-after-free in firmware_fallback_sysfs | Date | Tue, 13 Apr 2021 16:12:42 +0530 |
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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@syzkaller.appspotmail.com Tested-by: syzbot+de271708674e2093097b@syzkaller.appspotmail.com Signed-off-by: Anirudh Rayabharam <mail@anirudhrb.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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