From: Junrui Luo <moonafterrain@outlook.com> stable inclusion from stable-v6.6.140 commit 43a878639b90e9721ffa5eb616a7e6d8454adef3 category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/15250 CVE: CVE-2026-45999 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- [ Upstream commit 21e161de2dc660b1bb70ef5b156ab8e6e1cca3ab ] Some crafted images can have illegal (!partial_decoding && m_llen < m_plen) extents, and the LZ4 inplace decompression path can be wrongly hit, but it cannot handle (outpages < inpages) properly: "outpages - inpages" wraps to a large value and the subsequent rq->out[] access reads past the decompressed_pages array. However, such crafted cases can correctly result in a corruption report in the normal LZ4 non-inplace path. Let's add an additional check to fix this for backporting. Reproducible image (base64-encoded gzipped blob): H4sIAJGR12kCA+3SPUoDQRgG4MkmkkZk8QRbRFIIi9hbpEjrHQI5ghfwCN5BLCzTGtLbBI+g dilSJo1CnIm7GEXFxhT6PDDwfrs73/ywIQD/1ePD4r7Ou6ETsrq4mu7XcWfj++Pb58nJU/9i PNtbjhan04/9GtX4qVYc814WDqt6FaX5s+ZwXXeq52lndT6IuVvlblytLMvh4Gzwaf90nsvz 2DF/21+20T/ldgp5s1jXRaN4t/8izsy/OUB6e/Qa79r+JwAAAAAAAL52vQVuGQAAAP6+my1w ywAAAAAAAADwu14ATsEYtgBQAAA= $ mount -t erofs -o cache_strategy=disabled foo.erofs /mnt $ dd if=/mnt/data of=/dev/null bs=4096 count=1 Fixes: 598162d05080 ("erofs: support decompress big pcluster for lz4 backend") Reported-by: Yuhao Jiang <danisjiang@gmail.com> Cc: stable@vger.kernel.org Signed-off-by: Junrui Luo <moonafterrain@outlook.com> Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com> Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com> [ inverted condition to early-out `goto docopy` form and used `ctx->inpages`/`ctx->outpages` instead of `rq->` ] Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Hongbo Li <lihongbo22@huawei.com> --- fs/erofs/decompressor.c | 1 + 1 file changed, 1 insertion(+) diff --git a/fs/erofs/decompressor.c b/fs/erofs/decompressor.c index 86e088fd386e..18e4da98309d 100644 --- a/fs/erofs/decompressor.c +++ b/fs/erofs/decompressor.c @@ -133,6 +133,7 @@ static void *z_erofs_lz4_handle_overlap(struct z_erofs_lz4_decompress_ctx *ctx, if (rq->inplace_io) { omargin = PAGE_ALIGN(ctx->oend) - ctx->oend; if (rq->partial_decoding || !may_inplace || + ctx->outpages < ctx->inpages || omargin < LZ4_DECOMPRESS_INPLACE_MARGIN(rq->inputsize)) goto docopy; -- 2.34.1