Re: [Libguestfs] [libguestfs-common PATCH 2/2] detect_kernels: deal with RHEL's kernel-core / kernel-modules-core split

In "kernel-5.14.0-269.el9", the "kernel-modules-core" subpackage got split from the "kernel-core" subpackage. Therefore, a single binary RPM containing *both* the "/boot/vmlinuz-5.14.0-269.el9.x86_64" file *and* the "/lib/modules/5.14.0-269.el9.x86_64" directory no longer exists. The file now belongs to "kernel-core", and the directory to "kernel-modules-core". As a result, when we investigate the file list of "kernel-core" (based on "kernel-core" providing "/boot/vmlinuz-5.14.0-269.el9.x86_64"), the first match against "/lib/modules/" is not the actual module root directory "/lib/modules/5.14.0-269.el9.x86_64", but the nonsensical "/lib/modules/5.14.0-269.el9.x86_64/.vmlinuz.hmac" regular file. This latter file is never a directory, therefore we rule out "kernel-core" as a kernel package. We also rule out "kernel-modules-core" (even earlier) because it does not contain "/boot/vmlinuz-5.14.0-269.el9.x86_64". Now, the code already deals with the case if the prospective kernel package *does not provide a match* for the "/lib/modules/" prefix: in that case, we construct the modpath manually, from said prefix, and the version number found in "/boot/vmlinuz-<version>". This fallback is good, but it's unreachable if *there is* a candidate, it's just wrong (i.e., not a directory). Perform the "is_dir" check on the candidate modpath earlier, so that we can fall back to the manual modpath construction if the modpath candidate exists, but is wrong. With this, the original "is_dir" check becomes superfluous (duplicated) *except* when the "Not_found" branch is taken. Therefore, hoist the original "is_dir" check into that branch. Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2175703 Reported-by: Vera Wu <vwu(a)redhat.com&gt; Signed-off-by: Laszlo Ersek <lersek(a)redhat.com&gt; Tested-by: Vera Wu <vwu(a)redhat.com&gt; --- Notes: context:-U5 mldrivers/linux_kernels.ml | 24 +++++++++++++++----- 1 file changed, 18 insertions(+), 6 deletions(-) diff --git a/mldrivers/linux_kernels.ml b/mldrivers/linux_kernels.ml index 5b8bdee9923d..23ff76a5504c 100644 --- a/mldrivers/linux_kernels.ml +++ b/mldrivers/linux_kernels.ml @@ -125,31 +125,43 @@ let detect_kernels (g : G.guestfs) root bootloader apps = *) let modpath, version = let prefix = "/lib/modules/" in let prefix_len = String.length prefix in try - List.find_map ( + let modpath, version = List.find_map ( fun filename -> let filename_len = String.length filename in if filename_len > prefix_len && String.is_prefix filename prefix then ( let version = String.sub filename prefix_len (filename_len - prefix_len) in Some (filename, version) ) else None - ) files + ) files in + (* Fall back to the version in the vmlinuz file name not only if + * a candidate pathname couldn't be found under /lib/modules/, + * but also in case the candidate pathname doesn't reference a + * directory. See RHBZ#2175703. + * + * Note that this "is_dir" check is deliberately kept outside of + * the "find_map"'s mapper function above: we want the first + * candidate *to be* a directory, and not the first candidate + * *that is* a directory. + *) + if not (g#is_dir ~followsymlinks:true modpath) then + raise Not_found; + modpath, version with Not_found -> let version = String.sub vmlinuz 14 (String.length vmlinuz - 14) in let modpath = prefix ^ version in + (* Check that the modpath exists. *) + if not (g#is_dir ~followsymlinks:true modpath) then + raise Not_found; modpath, version in - (* Check that the modpath exists. *) - if not (g#is_dir ~followsymlinks:true modpath) then - raise Not_found; - (* Find the initramfs which corresponds to the kernel. * Since the initramfs is built at runtime, and doesn't have * to be covered by the RPM file list, this is basically * guesswork. *)