From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001 From: Daniel Axtens Date: Thu, 21 Jan 2021 00:05:58 +1100 Subject: [PATCH] io/gzio: Add init_dynamic_block() clean up if unpacking codes fails init_dynamic_block() didn't clean up gzio->tl and td in some error paths. This left td pointing to part of tl. Then in grub_gzio_close(), when tl was freed the storage for td would also be freed. The code then attempts to free td explicitly, performing a UAF and then a double free. Explicitly clean up tl and td in the error paths. Signed-off-by: Daniel Axtens Reviewed-by: Daniel Kiper --- grub-core/io/gzio.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/grub-core/io/gzio.c b/grub-core/io/gzio.c index 6e9b9c936..97b34f885 100644 --- a/grub-core/io/gzio.c +++ b/grub-core/io/gzio.c @@ -953,7 +953,7 @@ init_dynamic_block (grub_gzio_t gzio) if ((unsigned) i + j > n) { grub_error (GRUB_ERR_BAD_COMPRESSED_DATA, "too many codes found"); - return; + goto fail; } while (j--) ll[i++] = l; @@ -966,7 +966,7 @@ init_dynamic_block (grub_gzio_t gzio) if ((unsigned) i + j > n) { grub_error (GRUB_ERR_BAD_COMPRESSED_DATA, "too many codes found"); - return; + goto fail; } while (j--) ll[i++] = 0; @@ -981,7 +981,7 @@ init_dynamic_block (grub_gzio_t gzio) if ((unsigned) i + j > n) { grub_error (GRUB_ERR_BAD_COMPRESSED_DATA, "too many codes found"); - return; + goto fail; } while (j--) ll[i++] = 0; @@ -1019,6 +1019,12 @@ init_dynamic_block (grub_gzio_t gzio) /* indicate we're now working on a block */ gzio->code_state = 0; gzio->block_len++; + return; + + fail: + huft_free (gzio->tl); + gzio->td = NULL; + gzio->tl = NULL; }