On Fri, Apr 19, 2024 at 11:10:33AM +0100, Andrew Cooper wrote: > On 19/04/2024 11:02 am, Roger Pau Monne wrote: > > Livepatch payloads containing symbols that belong to init sections can only > > lead to page faults later on, as by the time the livepatch is loaded init > > sections have already been freed. > > > > Refuse to resolve such symbols and return an error instead. > > > > Note such resolutions are only relevant for symbols that point to undefined > > sections (SHN_UNDEF), as that implies the symbol is not in the current > > payload > > and hence must either be a Xen or a different livepatch payload symbol. > > > > Do not allow to resolve symbols that point to __init_begin, as that address > > is > > also unmapped. On the other hand, __init_end is not unmapped, and hence > > allow > > resolutions against it. > > > > Signed-off-by: Roger Pau Monné <roger....@citrix.com> > > Reviewed-by: Andrew Cooper <andrew.coop...@citrix.com>, although ... > > > --- > > Changes since v1: > > - Fix off-by-one in range checking. > > --- > > xen/common/livepatch_elf.c | 16 ++++++++++++++++ > > 1 file changed, 16 insertions(+) > > > > diff --git a/xen/common/livepatch_elf.c b/xen/common/livepatch_elf.c > > index 45d73912a3cd..a67101eadc02 100644 > > --- a/xen/common/livepatch_elf.c > > +++ b/xen/common/livepatch_elf.c > > @@ -4,6 +4,7 @@ > > > > #include <xen/errno.h> > > #include <xen/lib.h> > > +#include <xen/sections.h> > > #include <xen/symbols.h> > > #include <xen/livepatch_elf.h> > > #include <xen/livepatch.h> > > @@ -310,6 +311,21 @@ int livepatch_elf_resolve_symbols(struct livepatch_elf > > *elf) > > break; > > } > > } > > + > > + /* > > + * Ensure not an init symbol. Only applicable to Xen symbols, > > as > > + * livepatch payloads don't have init sections or equivalent. > > + */ > > + else if ( st_value >= (uintptr_t)&__init_begin && > > + st_value < (uintptr_t)&__init_end ) > > ... I normally vertically the (casts) in cases like this for improved > legibility. Happy to fold on commit.
Did this, but reverted afterwards because I wasn't sure whether it would go against the coding style. Aligning would be my preference also. Thanks, Roger.
