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Subject[tip:x86/urgent] x86/platform/UV: Fix bug with iounmap() of the UV4 EFI System Table causing a crash
Commit-ID:  e363d24c2b997c421476c6aa00547edadf678efe
Gitweb: http://git.kernel.org/tip/e363d24c2b997c421476c6aa00547edadf678efe
Author: Mike Travis <travis@sgi.com>
AuthorDate: Mon, 1 Aug 2016 13:40:51 -0500
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Wed, 10 Aug 2016 15:55:38 +0200

x86/platform/UV: Fix bug with iounmap() of the UV4 EFI System Table causing a crash

Save the uv_systab::size field before doing the iounmap()
of the struct pointer, to avoid a NULL dereference crash.

Tested-by: Frank Ramsay <framsay@sgi.com>
Tested-by: John Estabrook <estabrook@sgi.com>
Signed-off-by: Mike Travis <travis@sgi.com>
Reviewed-by: Dimitri Sivanich <sivanich@sgi.com>
Reviewed-by: Nathan Zimmer <nzimmer@sgi.com>
Cc: Alex Thorlton <athorlton@sgi.com>
Cc: Andrew Banman <abanman@sgi.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Russ Anderson <rja@sgi.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20160801184050.250424783@asylum.americas.sgi.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/platform/uv/bios_uv.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/arch/x86/platform/uv/bios_uv.c b/arch/x86/platform/uv/bios_uv.c
index 66b2166..4e9fd13 100644
--- a/arch/x86/platform/uv/bios_uv.c
+++ b/arch/x86/platform/uv/bios_uv.c
@@ -199,12 +199,14 @@ void uv_bios_init(void)
return;
}

+ /* Starting with UV4 the UV systab size is variable */
if (uv_systab->revision >= UV_SYSTAB_VERSION_UV4) {
+ int size = uv_systab->size;
+
iounmap(uv_systab);
- uv_systab = ioremap(efi.uv_systab, uv_systab->size);
+ uv_systab = ioremap(efi.uv_systab, size);
if (!uv_systab) {
- pr_err("UV: UVsystab: ioremap(%d) failed!\n",
- uv_systab->size);
+ pr_err("UV: UVsystab: ioremap(%d) failed!\n", size);
return;
}
}
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