Date: Mon, 18 Jan 2021 17:24:50 -0800 From: Ravi Pokala <rpokala@freebsd.org> To: Toomas Soome <tsoome@FreeBSD.org>, <src-committers@FreeBSD.org>, <dev-commits-src-all@FreeBSD.org>, <dev-commits-src-main@FreeBSD.org> Subject: Re: ad1ebbe5cea8 - main - loader: create local copy of mode list provided by vbeinfoblock Message-ID: <7FCB573F-0BC6-429E-919C-6A87513DBD63@panasas.com> In-Reply-To: <202101160823.10G8NjEi016925@gitrepo.freebsd.org> References: <202101160823.10G8NjEi016925@gitrepo.freebsd.org>
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Hi Toomas,
-----Original Message-----
From: <owner-src-committers@freebsd.org> on behalf of Toomas Soome <tsoome@FreeBSD.org>
Date: 2021-01-16, Saturday at 00:23
To: <src-committers@FreeBSD.org>, <dev-commits-src-all@FreeBSD.org>, <dev-commits-src-main@FreeBSD.org>
Subject: git: ad1ebbe5cea8 - main - loader: create local copy of mode list provided by vbeinfoblock
The branch main has been updated by tsoome:
URL: https://cgit.FreeBSD.org/src/commit/?id=ad1ebbe5cea8ffac0037966990ddf0f80faa55d5
commit ad1ebbe5cea8ffac0037966990ddf0f80faa55d5
Author: Toomas Soome <tsoome@FreeBSD.org>
AuthorDate: 2021-01-16 10:18:32 +0000
Commit: Toomas Soome <tsoome@FreeBSD.org>
CommitDate: 2021-01-16 10:23:22 +0000
loader: create local copy of mode list provided by vbeinfoblock
Apparently some systems do corrupt mode list memory area, so we need
to use local copy instead.
...
+ vbe_mode_list_size = (uintptr_t)p - (uintptr_t)ml;
+ vbe_mode_list = malloc(vbe_mode_list_size);
+ if (vbe_mode_list == NULL) {
+ free(vbe);
+ vbe = NULL;
+ free(vbe_mode);
+ vbe_mode = NULL;
+ }
+ bcopy(ml, vbe_mode_list, vbe_mode_list_size);
+
+ /* reset VideoModePtr, so we will not have chance to use bad data. */
+ vbe->VideoModePtr = 0;
If allocation of vbe_mode_list failed, you're freeing things that were allocated before it, but then you're continuing on. The very next thing you do is the bcopy(), which dereferences vbe_mode_list, which is NULL because of the allocation failure.
That doesn't seem right.
Thanks,
Ravi (rpokala@)
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