74f9c62794
Signed-off-by: Qiumiao Zhang <zhangqiumiao1@huawei.com> (cherry picked from commit c141a13130da5dca205b607533751a6ba6c9581e)
105 lines
3.1 KiB
Diff
105 lines
3.1 KiB
Diff
From abff01c61155a33c22d259c224ce2d7f9fae54f7 Mon Sep 17 00:00:00 2001
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From: B Horn <b@horn.uk>
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Date: Sun, 12 May 2024 03:26:19 +0100
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Subject: [PATCH 24/73] disk/loopback: Reference tracking for the loopback
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It was possible to delete a loopback while there were still references
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to it. This led to an exploitable use-after-free.
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Fixed by implementing a reference counting in the grub_loopback struct.
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Reported-by: B Horn <b@horn.uk>
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Signed-off-by: B Horn <b@horn.uk>
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Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
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---
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grub-core/disk/loopback.c | 18 ++++++++++++++++++
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include/grub/err.h | 1 +
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2 files changed, 19 insertions(+)
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diff --git a/grub-core/disk/loopback.c b/grub-core/disk/loopback.c
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index 4635dcf..2bea4e9 100644
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--- a/grub-core/disk/loopback.c
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+++ b/grub-core/disk/loopback.c
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@@ -24,6 +24,7 @@
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#include <grub/mm.h>
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#include <grub/extcmd.h>
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#include <grub/i18n.h>
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+#include <grub/safemath.h>
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GRUB_MOD_LICENSE ("GPLv3+");
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@@ -33,6 +34,7 @@ struct grub_loopback
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grub_file_t file;
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struct grub_loopback *next;
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unsigned long id;
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+ grub_uint64_t refcnt;
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};
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static struct grub_loopback *loopback_list;
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@@ -64,6 +66,8 @@ delete_loopback (const char *name)
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if (! dev)
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return grub_error (GRUB_ERR_BAD_DEVICE, "device not found");
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+ if (dev->refcnt > 0)
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+ return grub_error (GRUB_ERR_STILL_REFERENCED, "device still referenced");
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/* Remove the device from the list. */
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*prev = dev->next;
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@@ -120,6 +124,7 @@ grub_cmd_loopback (grub_extcmd_context_t ctxt, int argc, char **args)
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newdev->file = file;
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newdev->id = last_id++;
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+ newdev->refcnt = 0;
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/* Add the new entry to the list. */
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newdev->next = loopback_list;
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@@ -161,6 +166,9 @@ grub_loopback_open (const char *name, grub_disk_t disk)
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if (! dev)
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return grub_error (GRUB_ERR_UNKNOWN_DEVICE, "can't open device");
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+ if (grub_add (dev->refcnt, 1, &dev->refcnt))
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+ grub_fatal ("Reference count overflow");
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+
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/* Use the filesize for the disk size, round up to a complete sector. */
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if (dev->file->size != GRUB_FILE_SIZE_UNKNOWN)
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disk->total_sectors = ((dev->file->size + GRUB_DISK_SECTOR_SIZE - 1)
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@@ -178,6 +186,15 @@ grub_loopback_open (const char *name, grub_disk_t disk)
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return 0;
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}
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+static void
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+grub_loopback_close (grub_disk_t disk)
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+{
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+ struct grub_loopback *dev = disk->data;
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+
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+ if (grub_sub (dev->refcnt, 1, &dev->refcnt))
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+ grub_fatal ("Reference count underflow");
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+}
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+
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static grub_err_t
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grub_loopback_read (grub_disk_t disk, grub_disk_addr_t sector,
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grub_size_t size, char *buf)
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@@ -220,6 +237,7 @@ static struct grub_disk_dev grub_loopback_dev =
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.id = GRUB_DISK_DEVICE_LOOPBACK_ID,
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.disk_iterate = grub_loopback_iterate,
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.disk_open = grub_loopback_open,
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+ .disk_close = grub_loopback_close,
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.disk_read = grub_loopback_read,
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.disk_write = grub_loopback_write,
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.next = 0
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diff --git a/include/grub/err.h b/include/grub/err.h
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index 322d067..7a20749 100644
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--- a/include/grub/err.h
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+++ b/include/grub/err.h
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@@ -74,6 +74,7 @@ typedef enum
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GRUB_ERR_EOF,
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GRUB_ERR_BAD_SIGNATURE,
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GRUB_ERR_BAD_FIRMWARE,
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+ GRUB_ERR_STILL_REFERENCED,
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GRUB_ERR_TPCM_VERIFY
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}
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grub_err_t;
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--
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2.33.0
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