From 85307c34e895df5d8b3af23b765d878242c3cdc2 Mon Sep 17 00:00:00 2001 From: Glenn Washburn Date: Thu, 3 Dec 2020 19:57:11 -0600 Subject: [PATCH] loopback: Do not automaticaly replace existing loopback dev, error instead If there is a loopback device with the same name as the one to be created, instead of closing the old one and replacing it with the new one, return an error instead. If the loopback device was created, its probably being used by something and just replacing it may cause GRUB to crash unexpectedly. This fixes obvious problems like "loopback d (d)/somefile". Its not too onerous to force the user to delete the loopback first with the "-d" switch. Signed-off-by: Glenn Washburn Reviewed-by: Daniel Kiper --- grub-core/disk/loopback.c | 18 +++++------------- 1 file changed, 5 insertions(+), 13 deletions(-) diff --git a/grub-core/disk/loopback.c b/grub-core/disk/loopback.c index cdf9123fa..41bebd14f 100644 --- a/grub-core/disk/loopback.c +++ b/grub-core/disk/loopback.c @@ -92,24 +92,16 @@ grub_cmd_loopback (grub_extcmd_context_t ctxt, int argc, char **args) if (argc < 2) return grub_error (GRUB_ERR_BAD_ARGUMENT, N_("filename expected")); + /* Check that a device with requested name does not already exist. */ + for (newdev = loopback_list; newdev; newdev = newdev->next) + if (grub_strcmp (newdev->devname, args[0]) == 0) + return grub_error (GRUB_ERR_BAD_ARGUMENT, "device name already exists"); + file = grub_file_open (args[1], GRUB_FILE_TYPE_LOOPBACK | GRUB_FILE_TYPE_NO_DECOMPRESS); if (! file) return grub_errno; - /* First try to replace the old device. */ - for (newdev = loopback_list; newdev; newdev = newdev->next) - if (grub_strcmp (newdev->devname, args[0]) == 0) - break; - - if (newdev) - { - grub_file_close (newdev->file); - newdev->file = file; - - return 0; - } - /* Unable to replace it, make a new entry. */ newdev = grub_malloc (sizeof (struct grub_loopback)); if (! newdev) -- 2.47.2