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Thu, 18 Sep 2025 13:48:54 -0700 (PDT) Received: from crl-3.node2.local ([125.63.65.162]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-26980368ef4sm34486625ad.149.2025.09.18.13.48.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 18 Sep 2025 13:48:53 -0700 (PDT) From: Kriish Sharma To: agruenba@redhat.com Cc: gfs2@lists.linux.dev, linux-kernel@vger.kernel.org, skhan@linuxfoundation.org, david.hunter.linux@gmail.com, linux-kernel-mentees@lists.linux.dev, Kriish Sharma , syzbot+7567dc5c8aa8f68bde74@syzkaller.appspotmail.com Subject: [PATCH] gfs2: add bounds check for rd_length in compute_bitstructs() Date: Thu, 18 Sep 2025 20:48:30 +0000 Message-Id: <20250918204830.229918-1-kriish.sharma2006@gmail.com> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-kernel-mentees@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit compute_bitstructs() allocates an array of gfs2_bitmap structures using kcalloc(). The function only checked for length == 0 but did not guard against excessively large length values. If rd_length is too large, the multiplication inside kcalloc(length, sizeof(struct gfs2_bitmap), GFP_NOFS) can exceed KMALLOC_MAX_SIZE. This leads to the allocator calculating an order greater than MAX_ORDER when calling get_order(), which is invalid. As a result, __alloc_pages() warns about the bad request. This patch adds an explicit check that rd_length is not only non-zero but also within the maximum safe limit for kmalloc_array(): length <= KMALLOC_MAX_SIZE / sizeof(struct gfs2_bitmap) This ensures that get_order() is only ever called with a valid size, resulting in an allocation order within MAX_ORDER Fixes: b9158815de52 ("Merge tag 'char-misc-6.9-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc") Reported-by: syzbot+7567dc5c8aa8f68bde74@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=7567dc5c8aa8f68bde74 Signed-off-by: Kriish Sharma --- fs/gfs2/rgrp.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/gfs2/rgrp.c b/fs/gfs2/rgrp.c index 26d6c1eea559..a879e8030568 100644 --- a/fs/gfs2/rgrp.c +++ b/fs/gfs2/rgrp.c @@ -760,7 +760,7 @@ static int compute_bitstructs(struct gfs2_rgrpd *rgd) u32 bytes_left, bytes; int x; - if (!length) + if (!length || length > KMALLOC_MAX_SIZE / sizeof(struct gfs2_bitmap)) return -EINVAL; rgd->rd_bits = kcalloc(length, sizeof(struct gfs2_bitmap), GFP_NOFS); -- 2.34.1