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7.8 High

CVE-2024-49884 In the Linux kernel, the following vulnerability has been resolved: ext4: fix slab-use-after-free in…

Description

In the Linux kernel, the following vulnerability has been resolved: ext4: fix slab-use-after-free in ext4_split_extent_at() We hit the following use-after-free: ================================================================== BUG: KASAN: slab-use-after-free in ext4_split_extent_at+0xba8/0xcc0 Read of size 2 at addr ffff88810548ed08 by task kworker/u20:0/40 CPU: 0 PID: 40 Comm: kworker/u20:0 Not tainted 6.9.0-dirty #724 Call Trace: <TASK> kasan_report+0x93/0xc0 ext4_split_extent_at+0xba8/0xcc0 ext4_split_extent.isra.0+0x18f/0x500 ext4_split_convert_extents+0x275/0x750 ext4_ext_handle_unwritten_extents+0x73e/0x1580 ext4_ext_map_blocks+0xe20/0x2dc0 ext4_map_blocks+0x724/0x1700 ext4_do_writepages+0x12d6/0x2a70 [...] Allocated by task 40: __kmalloc_noprof+0x1ac/0x480 ext4_find_extent+0xf3b/0x1e70 ext4_ext_map_blocks+0x188/0x2dc0 ext4_map_blocks+0x724/0x1700 ext4_do_writepages+0x12d6/0x2a70 [...] Freed by task 40: kfree+0xf1/0x2b0 ext4_find_extent+0xa71/0x1e70 ext4_ext_insert_extent+0xa22/0x3260 ext4_split_extent_at+0x3ef/0xcc0 ext4_split_extent.isra.0+0x18f/0x500 ext4_split_convert_extents+0x275/0x750 ext4_ext_handle_unwritten_extents+0x73e/0x1580 ext4_ext_map_blocks+0xe20/0x2dc0 ext4_map_blocks+0x724/0x1700 ext4_do_writepages+0x12d6/0x2a70 [...] ================================================================== The flow of issue triggering is as follows: ext4_split_extent_at path = *ppath ext4_ext_insert_extent(ppath) ext4_ext_create_new_leaf(ppath) ext4_find_extent(orig_path) path = *orig_path read_extent_tree_block // return -ENOMEM or -EIO ext4_free_ext_path(path) kfree(path) *orig_path = NULL a. If err is -ENOMEM: ext4_ext_dirty(path + path->p_depth) // path use-after-free !!! b. If err is -EIO and we have EXT_DEBUG defined: ext4_ext_show_leaf(path) eh = path[depth].p_hdr // path also use-after-free !!! So when trying to zeroout or fix the extent length, call ext4_find_extent() to update the path. In addition we use *ppath directly as an ext4_ext_show_leaf() input to avoid possible use-after-free when EXT_DEBUG is defined, and to avoid unnecessary path updates.

Affected products and versions

Product Affected versions Fixed in
Linux 6.12 earliest → < 6.12 6.12
Linux 6.11 earliest → < 6.11.3 6.11.3
Linux 6.10 earliest → < 6.10.14 6.10.14
Linux 6.6 earliest → < 6.6.55 6.6.55
Linux 6.1 earliest → < 6.1.113 6.1.113
Linux 5.15 earliest → < 5.15.168 5.15.168
Linux 5.10 earliest → < 5.10.227 5.10.227
Linux 5.4 earliest → < 5.4.290 5.4.290
Linux 4.19 earliest → < 4.19.323 4.19.323
Show the 7 other branches
Product Affected versions Fixed in
Linux 3.18 No fix stated
SIMATIC S7-1500 CPU 1518-4 PN/DP MFP 3.1 3.1.0 → < 3.1.5 3.1.5
SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP 3.1 3.1.0 → < 3.1.5 3.1.5
SIPLUS S7-1500 CPU 1518-4 PN/DP MFP 3.1 3.1.0 → < 3.1.5 3.1.5
RUGGEDCOM RST2428P 3.2 earliest → < 3.2 3.2
SCALANCE XC-300/XR-300/XC-400/XR-500WG/XR-500 family 3.2 earliest → < 3.2 3.2
SCALANCE XCM-/XRM-/XCH-/XRH-300 family 3.2 earliest → < 3.2 3.2

References

Timeline

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