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authorTianyu Lan <Tianyu.Lan@microsoft.com>2019-09-02 20:41:43 +0800
committerIngo Molnar <mingo@kernel.org>2019-09-02 19:57:19 +0200
commit4030b4c585c41eeefec7bd20ce3d0e100a0f2e4d (patch)
tree7690ee68cc3ce82fba4c4410d601cf999b68cc72 /arch/x86/hyperv
parent9b8bd476e78e89c9ea26c3b435ad0201c3d7dbf5 (diff)
downloadlinux-4030b4c585c41eeefec7bd20ce3d0e100a0f2e4d.tar.bz2
x86/hyper-v: Fix overflow bug in fill_gva_list()
When the 'start' parameter is >= 0xFF000000 on 32-bit systems, or >= 0xFFFFFFFF'FF000000 on 64-bit systems, fill_gva_list() gets into an infinite loop. With such inputs, 'cur' overflows after adding HV_TLB_FLUSH_UNIT and always compares as less than end. Memory is filled with guest virtual addresses until the system crashes. Fix this by never incrementing 'cur' to be larger than 'end'. Reported-by: Jong Hyun Park <park.jonghyun@yonsei.ac.kr> Signed-off-by: Tianyu Lan <Tianyu.Lan@microsoft.com> Reviewed-by: Michael Kelley <mikelley@microsoft.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Fixes: 2ffd9e33ce4a ("x86/hyper-v: Use hypercall for remote TLB flush") Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/hyperv')
-rw-r--r--arch/x86/hyperv/mmu.c8
1 files changed, 5 insertions, 3 deletions
diff --git a/arch/x86/hyperv/mmu.c b/arch/x86/hyperv/mmu.c
index e65d7fe6489f..5208ba49c89a 100644
--- a/arch/x86/hyperv/mmu.c
+++ b/arch/x86/hyperv/mmu.c
@@ -37,12 +37,14 @@ static inline int fill_gva_list(u64 gva_list[], int offset,
* Lower 12 bits encode the number of additional
* pages to flush (in addition to the 'cur' page).
*/
- if (diff >= HV_TLB_FLUSH_UNIT)
+ if (diff >= HV_TLB_FLUSH_UNIT) {
gva_list[gva_n] |= ~PAGE_MASK;
- else if (diff)
+ cur += HV_TLB_FLUSH_UNIT;
+ } else if (diff) {
gva_list[gva_n] |= (diff - 1) >> PAGE_SHIFT;
+ cur = end;
+ }
- cur += HV_TLB_FLUSH_UNIT;
gva_n++;
} while (cur < end);