[xen master] livepatch: Tighten alignment checks.

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[xen master] livepatch: Tighten alignment checks.

patchbot
commit c3f951417f8837e9e2061e592e9cce95bd09095b
Author:     Konrad Rzeszutek Wilk <[hidden email]>
AuthorDate: Fri Jun 23 12:41:45 2017 -0400
Commit:     Konrad Rzeszutek Wilk <[hidden email]>
CommitDate: Thu Oct 5 09:27:32 2017 -0400

    livepatch: Tighten alignment checks.
   
    The ELF specification mentions nothing about the sh_size being
    modulo the sh_addralign. Only that sh_addr MUST be aligned on
    sh_addralign if sh_addralign is not zero or one.
   
    We on loading did not take this in-to account so this patch adds
    a check on the ELF file as it is being parsed.
   
    Reviewed-by: Jan Beulich <[hidden email]>
    Signed-off-by: Konrad Rzeszutek Wilk <[hidden email]>
---
 xen/common/livepatch_elf.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/xen/common/livepatch_elf.c b/xen/common/livepatch_elf.c
index b69e271..dd8b47a 100644
--- a/xen/common/livepatch_elf.c
+++ b/xen/common/livepatch_elf.c
@@ -86,6 +86,19 @@ static int elf_resolve_sections(struct livepatch_elf *elf, const void *data)
                     delta < sizeof(Elf_Ehdr) ? "at ELF header" : "is past end");
             return -EINVAL;
         }
+        else if ( sec[i].sec->sh_addralign & (sec[i].sec->sh_addralign - 1) )
+        {
+            dprintk(XENLOG_ERR, LIVEPATCH "%s: Section [%u] alignment (%#"PRIxElfAddr") is not supported\n",
+                    elf->name, i, sec[i].sec->sh_addralign);
+            return -EOPNOTSUPP;
+        }
+        else if ( sec[i].sec->sh_addralign &&
+                  sec[i].sec->sh_addr % sec[i].sec->sh_addralign )
+        {
+            dprintk(XENLOG_ERR, LIVEPATCH "%s: Section [%u] addr (%#"PRIxElfAddr") is not aligned properly (%#"PRIxElfAddr")\n",
+                    elf->name, i, sec[i].sec->sh_addr, sec[i].sec->sh_addralign);
+            return -EINVAL;
+        }
         else if ( (sec[i].sec->sh_flags & (SHF_WRITE | SHF_ALLOC)) &&
                   sec[i].sec->sh_type == SHT_NOBITS &&
                   sec[i].sec->sh_size > LIVEPATCH_MAX_SIZE )
--
generated by git-patchbot for /home/xen/git/xen.git#master

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