From: Andrew Price <anprice@redhat.com> stable inclusion from stable-v6.12.43 commit 53a0249d68a210c16e961b83adfa82f94ee0a53d category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/ICWGGP CVE: CVE-2025-38710 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- [ Upstream commit 557c024ca7250bb65ae60f16c02074106c2f197b ] A fuzzer test introduced corruption that ends up with a depth of 0 in dir_e_read(), causing an undefined shift by 32 at: index = hash >> (32 - dip->i_depth); As calculated in an open-coded way in dir_make_exhash(), the minimum depth for an exhash directory is ilog2(sdp->sd_hash_ptrs) and 0 is invalid as sdp->sd_hash_ptrs is fixed as sdp->bsize / 16 at mount time. So we can avoid the undefined behaviour by checking for depth values lower than the minimum in gfs2_dinode_in(). Values greater than the maximum are already being checked for there. Also switch the calculation in dir_make_exhash() to use ilog2() to clarify how the depth is calculated. Tested with the syzkaller repro.c and xfstests '-g quick'. Reported-by: syzbot+4708579bb230a0582a57@syzkaller.appspotmail.com Fixes: b3b94faa5fe5 ("[GFS2] The core of GFS2") Signed-off-by: Andrew Price <anprice@redhat.com> Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com> Signed-off-by: Sasha Levin <sashal@kernel.org> Conflicts: fs/gfs2/glops.c [Simple context conflicts do not affect this patch.] Signed-off-by: Zizhi Wo <wozizhi@huawei.com> --- fs/gfs2/dir.c | 6 ++---- fs/gfs2/glops.c | 5 +++++ 2 files changed, 7 insertions(+), 4 deletions(-) diff --git a/fs/gfs2/dir.c b/fs/gfs2/dir.c index e37002560c11..0cf704b2b08a 100644 --- a/fs/gfs2/dir.c +++ b/fs/gfs2/dir.c @@ -63,6 +63,7 @@ #include <linux/crc32.h> #include <linux/vmalloc.h> #include <linux/bio.h> +#include <linux/log2.h> #include "gfs2.h" #include "incore.h" @@ -914,7 +915,6 @@ static int dir_make_exhash(struct inode *inode) struct qstr args; struct buffer_head *bh, *dibh; struct gfs2_leaf *leaf; - int y; u32 x; __be64 *lp; u64 bn; @@ -981,9 +981,7 @@ static int dir_make_exhash(struct inode *inode) i_size_write(inode, sdp->sd_sb.sb_bsize / 2); gfs2_add_inode_blocks(&dip->i_inode, 1); dip->i_diskflags |= GFS2_DIF_EXHASH; - - for (x = sdp->sd_hash_ptrs, y = -1; x; x >>= 1, y++) ; - dip->i_depth = y; + dip->i_depth = ilog2(sdp->sd_hash_ptrs); gfs2_dinode_out(dip, dibh->b_data); diff --git a/fs/gfs2/glops.c b/fs/gfs2/glops.c index c63bee9adb6a..be6839451aaf 100644 --- a/fs/gfs2/glops.c +++ b/fs/gfs2/glops.c @@ -14,6 +14,7 @@ #include <linux/bio.h> #include <linux/posix_acl.h> #include <linux/security.h> +#include <linux/log2.h> #include "gfs2.h" #include "incore.h" @@ -337,6 +338,7 @@ static int inode_go_demote_ok(const struct gfs2_glock *gl) static int gfs2_dinode_in(struct gfs2_inode *ip, const void *buf) { + struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode); const struct gfs2_dinode *str = buf; struct timespec64 atime; u16 height, depth; @@ -383,6 +385,9 @@ static int gfs2_dinode_in(struct gfs2_inode *ip, const void *buf) depth = be16_to_cpu(str->di_depth); if (unlikely(depth > GFS2_DIR_MAX_DEPTH)) goto corrupt; + if ((ip->i_diskflags & GFS2_DIF_EXHASH) && + depth < ilog2(sdp->sd_hash_ptrs)) + goto corrupt; ip->i_depth = (u8)depth; ip->i_entries = be32_to_cpu(str->di_entries); -- 2.39.2