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kexec: copy only happens before uchunk goes to zero 

When loading segments, ubytes is <= mbytes.  When ubytes is exhausted,
there could be remaining mbytes.  Then in the while loop, the buf pointer
advancing with mchunk will causing meaningless reading even though it
doesn't harm.

So let's change to make sure that all of the copying and the rest only
happens before uchunk goes to zero.

Link: https://lkml.kernel.org/r/20240222092119.5602-1-gaoshanliukou@163.com
Signed-off-by: yang.zhang <yang.zhang@hexintek.com>
Acked-by: Baoquan He <bhe@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
yang.zhang 2024-02-22 17:21:19 +08:00 committed by Andrew Morton
parent a436184e3b
commit 4bb7be96fc
1 changed files with 24 additions and 20 deletions
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44
kernel/kexec_core.c
View File

@ -800,22 +800,24 @@ static int kimage_load_normal_segment(struct kimage *image,
PAGE_SIZE - (maddr & ~PAGE_MASK));
uchunk = min(ubytes, mchunk);
/* For file based kexec, source pages are in kernel memory */
if (image->file_mode)
memcpy(ptr, kbuf, uchunk);
else
result = copy_from_user(ptr, buf, uchunk);
if (uchunk) {
/* For file based kexec, source pages are in kernel memory */
if (image->file_mode)
memcpy(ptr, kbuf, uchunk);
else
result = copy_from_user(ptr, buf, uchunk);
ubytes -= uchunk;
if (image->file_mode)
kbuf += uchunk;
else
buf += uchunk;
}
kunmap_local(ptr);
if (result) {
result = -EFAULT;
goto out;
}
ubytes -= uchunk;
maddr += mchunk;
if (image->file_mode)
kbuf += mchunk;
else
buf += mchunk;
mbytes -= mchunk;
cond_resched();
@ -866,11 +868,18 @@ static int kimage_load_crash_segment(struct kimage *image,
memset(ptr + uchunk, 0, mchunk - uchunk);
}
/* For file based kexec, source pages are in kernel memory */
if (image->file_mode)
memcpy(ptr, kbuf, uchunk);
else
result = copy_from_user(ptr, buf, uchunk);
if (uchunk) {
/* For file based kexec, source pages are in kernel memory */
if (image->file_mode)
memcpy(ptr, kbuf, uchunk);
else
result = copy_from_user(ptr, buf, uchunk);
ubytes -= uchunk;
if (image->file_mode)
kbuf += uchunk;
else
buf += uchunk;
}
kexec_flush_icache_page(page);
kunmap_local(ptr);
arch_kexec_pre_free_pages(page_address(page), 1);
@ -878,12 +887,7 @@ static int kimage_load_crash_segment(struct kimage *image,
result = -EFAULT;
goto out;
}
ubytes -= uchunk;
maddr += mchunk;
if (image->file_mode)
kbuf += mchunk;
else
buf += mchunk;
mbytes -= mchunk;
cond_resched();