From: Pavel Tatashin <pasha.tatashin@soleen.com> [ Upstream commit 141f8202cfa4192c3af79b6cbd68e7760bb01b5a ] The ppos points to a position in the old kernel memory (and in case of arm64 in the crash kernel since elfcorehdr is passed as a segment). The function should update the ppos by the amount that was read. This bug is not exposed by accident, but other platforms update this value properly. So, fix it in ARM64 version of elfcorehdr_read() as well. Signed-off-by: Pavel Tatashin <pasha.tatashin@soleen.com> Fixes: e62aaeac426a ("arm64: kdump: provide /proc/vmcore file") Reviewed-by: Tyler Hicks <tyhicks@linux.microsoft.com> Link: https://lore.kernel.org/r/20210319205054.743368-1-pasha.tatashin@soleen.com Signed-off-by: Will Deacon <will@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Yang Yingliang <yangyingliang@huawei.com> --- arch/arm64/kernel/crash_dump.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/arch/arm64/kernel/crash_dump.c b/arch/arm64/kernel/crash_dump.c index f46d57c314430..76905a2585505 100644 --- a/arch/arm64/kernel/crash_dump.c +++ b/arch/arm64/kernel/crash_dump.c @@ -67,5 +67,7 @@ ssize_t copy_oldmem_page(unsigned long pfn, char *buf, ssize_t elfcorehdr_read(char *buf, size_t count, u64 *ppos) { memcpy(buf, phys_to_virt((phys_addr_t)*ppos), count); + *ppos += count; + return count; } -- 2.25.1