CC Andrew On 02/22/24 at 05:21pm, yang.zhang wrote: > From: "yang.zhang" <[email protected]> > > 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. > > Acked-by: Baoquan He <[email protected]> > Signed-off-by: yang.zhang <[email protected]> > > --- > V2 -> V3: > - Add more detailed description in the commit message > v1 -> v2: > - Only copy before uchunk goes to zero > > V1: https://lore.kernel.org/lkml/[email protected]/ > --- > kernel/kexec_core.c | 44 ++++++++++++++++++++++++-------------------- > 1 file changed, 24 insertions(+), 20 deletions(-) > > diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c > index d08fc7b5db97..2fc3d0e3715a 100644 > --- a/kernel/kexec_core.c > +++ b/kernel/kexec_core.c > @@ -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(); > -- > 2.25.1 >
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