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[dunfell,08/14] kernel: Fix path comparison in kernel staging dir symlinking

Message ID 27a982807caa7ffbdf2d4ef02bc0b037150b1b3b.1694526588.git.steve@sakoman.com
State Accepted, archived
Commit 27a982807caa7ffbdf2d4ef02bc0b037150b1b3b
Headers show
Series [dunfell,01/14] bind: Backport fix for CVE-2023-2828 | expand

Commit Message

Steve Sakoman Sept. 12, 2023, 1:53 p.m. UTC 
From: Staffan Rydén <staffan.ryden@axis.com>

Due to an oversight in the do_symlink_kernsrc function, the path
comparison between "S" and "STAGING_KERNEL_DIR" is broken. The code
obtains both variables, but modifies the local copy of "S" before
comparing them, causing the comparison to always return false.

This can cause the build to fail when the EXTERNALSRC flag is enabled,
since the code will try to create a symlink even if one already exists.

This patch resolves the issue by comparing the variables before they are
modified.

Signed-off-by: Staffan Rydén <staffan.ryden@axis.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
(cherry picked from commit afd2038ef8a66a5e6433be31a14e1eb0d9f9a1d3)
Signed-off-by: Steve Sakoman <steve@sakoman.com>
---
 meta/classes/kernel.bbclass | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)
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Patch

diff --git a/meta/classes/kernel.bbclass b/meta/classes/kernel.bbclass
index 5d8b3b062a..ba5b6cf384 100644
--- a/meta/classes/kernel.bbclass
+++ b/meta/classes/kernel.bbclass
@@ -143,13 +143,14 @@  do_unpack[cleandirs] += " ${S} ${STAGING_KERNEL_DIR} ${B} ${STAGING_KERNEL_BUILD
 do_clean[cleandirs] += " ${S} ${STAGING_KERNEL_DIR} ${B} ${STAGING_KERNEL_BUILDDIR}"
 python do_symlink_kernsrc () {
     s = d.getVar("S")
-    if s[-1] == '/':
-        # drop trailing slash, so that os.symlink(kernsrc, s) doesn't use s as directory name and fail
-        s=s[:-1]
     kernsrc = d.getVar("STAGING_KERNEL_DIR")
     if s != kernsrc:
         bb.utils.mkdirhier(kernsrc)
         bb.utils.remove(kernsrc, recurse=True)
+        if s[-1] == '/':
+            # drop trailing slash, so that os.symlink(kernsrc, s) doesn't use s as
+            # directory name and fail
+            s = s[:-1]
         if d.getVar("EXTERNALSRC"):
             # With EXTERNALSRC S will not be wiped so we can symlink to it
             os.symlink(s, kernsrc)