linux-kernel - [tip: efi/urgent] efivarfs: Don't return -EINTR when rate-limiting reads

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Date:   Fri, 19 Jun 2020 16:46:00 -0000
From:   "tip-bot2 for Tony Luck" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Lennart Poettering <mzxreary@...inter.de>,
        Tony Luck <tony.luck@...el.com>,
        Ard Biesheuvel <ardb@...nel.org>, x86 <x86@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: [tip: efi/urgent] efivarfs: Don't return -EINTR when rate-limiting reads

The following commit has been merged into the efi/urgent branch of tip:

Commit-ID:     4353f03317fd3eb0bd803b61bdb287b68736a728
Gitweb:        https://git.kernel.org/tip/4353f03317fd3eb0bd803b61bdb287b68736a728
Author:        Tony Luck <tony.luck@...el.com>
AuthorDate:    Thu, 28 May 2020 12:49:05 -07:00
Committer:     Ard Biesheuvel <ardb@...nel.org>
CommitterDate: Mon, 15 Jun 2020 14:38:56 +02:00

efivarfs: Don't return -EINTR when rate-limiting reads

Applications that read EFI variables may see a return
value of -EINTR if they exceed the rate limit and a
signal delivery is attempted while the process is sleeping.

This is quite surprising to the application, which probably
doesn't have code to handle it.

Change the interruptible sleep to a non-interruptible one.

Reported-by: Lennart Poettering <mzxreary@...inter.de>
Signed-off-by: Tony Luck <tony.luck@...el.com>
Link: https://lore.kernel.org/r/20200528194905.690-3-tony.luck@intel.com
Signed-off-by: Ard Biesheuvel <ardb@...nel.org>
---
 fs/efivarfs/file.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/fs/efivarfs/file.c b/fs/efivarfs/file.c
index 4b8bc45..feaa5e1 100644
--- a/fs/efivarfs/file.c
+++ b/fs/efivarfs/file.c
@@ -73,10 +73,8 @@ static ssize_t efivarfs_file_read(struct file *file, char __user *userbuf,
 	ssize_t size = 0;
 	int err;
 
-	while (!__ratelimit(&file->f_cred->user->ratelimit)) {
-		if (!msleep_interruptible(50))
-			return -EINTR;
-	}
+	while (!__ratelimit(&file->f_cred->user->ratelimit))
+		msleep(50);
 
 	err = efivar_entry_size(var, &datasize);