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systemd: lock disks while running filesystem checks #18653

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5 changes: 4 additions & 1 deletion SPECS-SIGNED/systemd-boot-signed/systemd-boot-signed.spec
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Original file line number Diff line number Diff line change
Expand Up @@ -20,7 +20,7 @@ Version: 255
# determine the build information from local checkout
Version: %(tools/meson-vcs-tag.sh . error | sed -r 's/-([0-9])/.^\1/; s/-g/_g/')
%endif
Release: 34%{?dist}
Release: 35%{?dist}
License: LGPL-2.1-or-later AND MIT AND GPL-2.0-or-later
Vendor: Microsoft Corporation
Distribution: Azure Linux
Expand Down Expand Up @@ -98,6 +98,9 @@ popd
/boot/efi/EFI/BOOT/%{grubefiname}

%changelog
* Fri Aug 28 2026 Pawel Winogrodzki <pawelwi@microsoft.com> - 255-35
- Bump release to match systemd spec.

* Mon Aug 17 2026 Aditya Singh <v-aditysing@microsoft.com> - 255-34
- Bump release to match systemd spec.

Expand Down
77 changes: 77 additions & 0 deletions SPECS/systemd/systemd-fsck-lock-whole-disk.patch
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Original file line number Diff line number Diff line change
@@ -0,0 +1,77 @@
diff --git a/src/fsck/fsck.c b/src/fsck/fsck.c
index 000ed69..8eb209a 100644
--- a/src/fsck/fsck.c
+++ b/src/fsck/fsck.c
@@ -15,6 +15,7 @@
#include "sd-device.h"

#include "alloc-util.h"
+#include "blockdev-util.h"
#include "bus-common-errors.h"
#include "bus-error.h"
#include "bus-locator.h"
@@ -23,6 +24,7 @@
#include "fd-util.h"
#include "fs-util.h"
#include "fsck-util.h"
+#include "lock-util.h"
#include "main-func.h"
#include "parse-util.h"
#include "path-util.h"
@@ -233,8 +235,45 @@ static int fsck_progress_socket(void) {
return TAKE_FD(fd);
}

+static int lock_whole_disk(const char *device) {
+ _cleanup_free_ char *whole_disk = NULL;
+ _cleanup_close_ int fd = -EBADF;
+ struct stat st;
+ dev_t devno;
+ int r;
+
+ assert(device);
+
+ r = path_get_whole_disk(device, /* backing = */ false, &devno);
+ if (r < 0)
+ return log_error_errno(r, "Failed to find whole block device for '%s': %m", device);
+
+ r = devname_from_devnum(S_IFBLK, devno, &whole_disk);
+ if (r < 0)
+ return log_error_errno(r, "Failed to resolve whole block device for '%s': %m", device);
+
+ fd = open(whole_disk, O_RDONLY|O_CLOEXEC|O_NONBLOCK|O_NOCTTY);
+ if (fd < 0)
+ return log_error_errno(errno, "Failed to open whole block device '%s': %m", whole_disk);
+
+ if (fstat(fd, &st) < 0)
+ return log_error_errno(errno, "Failed to stat whole block device '%s': %m", whole_disk);
+ if (!S_ISBLK(st.st_mode) || st.st_rdev != devno)
+ return log_error_errno(SYNTHETIC_ERRNO(ENXIO),
+ "Path '%s' no longer refers to block device %u:%u.",
+ whole_disk, major(devno), minor(devno));
+
+ r = lock_generic(fd, LOCK_BSD, LOCK_EX);
+ if (r < 0)
+ return log_error_errno(r, "Failed to lock whole block device '%s': %m", whole_disk);
+
+ log_debug("Locked whole block device %s while checking %s.", whole_disk, device);
+ return TAKE_FD(fd);
+}
+
static int run(int argc, char *argv[]) {
_cleanup_close_pair_ int progress_pipe[2] = EBADF_PAIR;
+ _cleanup_close_ int lock_fd = -EBADF;
_cleanup_(sd_device_unrefp) sd_device *dev = NULL;
_cleanup_free_ char *dpath = NULL;
_cleanup_fclose_ FILE *console = NULL;
@@ -333,6 +372,10 @@ static int run(int argc, char *argv[]) {
}
}

+ lock_fd = lock_whole_disk(device);
+ if (lock_fd < 0)
+ return lock_fd;
+
console = fopen("/dev/console", "we");
if (console &&
arg_show_progress &&
13 changes: 12 additions & 1 deletion SPECS/systemd/systemd.spec
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Original file line number Diff line number Diff line change
Expand Up @@ -50,7 +50,7 @@ Version: 255
# determine the build information from local checkout
Version: %(tools/meson-vcs-tag.sh . error | sed -r 's/-([0-9])/.^\1/; s/-g/_g/')
%endif
Release: 34%{?dist}
Release: 35%{?dist}

# FIXME - hardcode to 'stable' for now as that's what we have in our blobstore
%global stable 1
Expand Down Expand Up @@ -162,6 +162,13 @@ Patch0914: Prevent-corruption-from-stale-alias-state-on-daemon-reload.patch
Patch0915: CVE-2026-15059.patch
Patch0916: CVE-2026-16742.patch

# Alternative to the proposed native e2fsprogs whole-disk lock:
# https://lore.kernel.org/linux-ext4/20260824161512.1332649-1-naraghavan@linux.microsoft.com/
# Do not ship both implementations. systemd-fsck retains its exclusive
# lock while waiting for fsck; native e2fsck locking would then block on
# a second independently-opened lock and deadlock boot.
Patch0917: systemd-fsck-lock-whole-disk.patch

%ifarch %{ix86} x86_64 aarch64
%global want_bootloader 1
%endif
Expand Down Expand Up @@ -1259,6 +1266,10 @@ rm -f %{name}.lang
# %autochangelog. So we need to continue manually maintaining the
# changelog here.
%changelog
* Fri Aug 28 2026 Pawel Winogrodzki <pawelwi@microsoft.com> - 255-35
- Lock the whole disk in systemd-fsck while its child fsck process checks
the filesystem.

* Thu Aug 13 2026 Azure Linux Security Servicing Account <azurelinux-security@microsoft.com> - 255-34
- Patch for CVE-2026-16742, CVE-2026-15059

Expand Down
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