6.12-stable review patch. If anyone has any objections, please let me know.
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From: Andrew Price anprice@redhat.com
[ 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 Signed-off-by: Andrew Price anprice@redhat.com Signed-off-by: Andreas Gruenbacher agruenba@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/gfs2/dir.c | 6 ++---- fs/gfs2/glops.c | 6 ++++++ 2 files changed, 8 insertions(+), 4 deletions(-)
diff --git a/fs/gfs2/dir.c b/fs/gfs2/dir.c index dbf1aede744c..509e2f0d97e7 100644 --- a/fs/gfs2/dir.c +++ b/fs/gfs2/dir.c @@ -60,6 +60,7 @@ #include <linux/crc32.h> #include <linux/vmalloc.h> #include <linux/bio.h> +#include <linux/log2.h>
#include "gfs2.h" #include "incore.h" @@ -912,7 +913,6 @@ 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; @@ -979,9 +979,7 @@ 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 4b6b23c638e2..1ed42f0e6ec7 100644 --- a/fs/gfs2/glops.c +++ b/fs/gfs2/glops.c @@ -11,6 +11,7 @@ #include <linux/bio.h> #include <linux/posix_acl.h> #include <linux/security.h> +#include <linux/log2.h>
#include "gfs2.h" #include "incore.h" @@ -450,6 +451,11 @@ static int gfs2_dinode_in(struct gfs2_inode *ip, const void *buf) gfs2_consist_inode(ip); return -EIO; } + if ((ip->i_diskflags & GFS2_DIF_EXHASH) && + depth < ilog2(sdp->sd_hash_ptrs)) { + gfs2_consist_inode(ip); + return -EIO; + } ip->i_depth = (u8)depth; ip->i_entries = be32_to_cpu(str->di_entries);