Gregory Price wrote: > walk_system_ram_res_rev() erroneously discards resource flags when > passing the information to the callback. > > This causes systems with IORESOURCE_SYSRAM_DRIVER_MANAGED memory to > have these resources selected during kexec to store kexec buffers > if that memory happens to be at placed above normal system ram. > > This leads to undefined behavior after reboot. If the kexec buffer > is never touched, nothing happens. If the kexec buffer is touched, > it could lead to a crash (like below) or undefined behavior. > > Tested on a system with CXL memory expanders with driver managed > memory, TPM enabled, and CONFIG_IMA_KEXEC=y. Adding printk's > showed the flags were being discarded and as a result the check > for IORESOURCE_SYSRAM_DRIVER_MANAGED passes. > > find_next_iomem_res: name(System RAM (kmem)) > start(10000000000) > end(1034fffffff) > flags(83000200) > > locate_mem_hole_top_down: start(10000000000) end(1034fffffff) flags(0) > [..] > Link: https://lore.kernel.org/all/20231114091658.228030-1-bhe@xxxxxxxxxx/ > Fixes: 7acf164b259d ("resource: add walk_system_ram_res_rev()") > Cc: stable@xxxxxxxxxxxxxxx > Signed-off-by: Gregory Price <gourry@xxxxxxxxxx> > --- > kernel/resource.c | 4 +--- > 1 file changed, 1 insertion(+), 3 deletions(-) > > diff --git a/kernel/resource.c b/kernel/resource.c > index b730bd28b422..4101016e8b20 100644 > --- a/kernel/resource.c > +++ b/kernel/resource.c > @@ -459,9 +459,7 @@ int walk_system_ram_res_rev(u64 start, u64 end, void *arg, > rams_size += 16; > } > > - rams[i].start = res.start; > - rams[i++].end = res.end; > - > + rams[i++] = res; > start = res.end + 1; Looks good to me, makes it obvious that everything that find_next_iomem_res() would return for walk_system_ram_range() users is the same as what walk_system_ram_res_rev() returns. Reviewed-by: Dan Williams <dan.j.williams@xxxxxxxxx>
