kernel/linux.git/lib, branch v6.1.124

lib: stackinit: hide never-taken branch from compiler

2024-12-14T18:54:37+00:00

commit 5c3793604f91123bf49bc792ce697a0bef4c173c upstream. The never-taken branch leads to an invalid bounds condition, which is by design. To avoid the unwanted warning from the compiler, hide the variable from the optimizer. ../lib/stackinit_kunit.c: In function 'do_nothing_u16_zero': ../lib/stackinit_kunit.c:51:49: error: array subscript 1 is outside array bounds of 'u16[0]' {aka 'short unsigned int[]'} [-Werror=array-bounds=] 51 | #define DO_NOTHING_RETURN_SCALAR(ptr) *(ptr) | ^~~~~~ ../lib/stackinit_kunit.c:219:24: note: in expansion of macro 'DO_NOTHING_RETURN_SCALAR' 219 | return DO_NOTHING_RETURN_ ## which(ptr + 1); \ | ^~~~~~~~~~~~~~~~~~ Link: https://lkml.kernel.org/r/20241117113813.work.735-kees@kernel.org Signed-off-by: Kees Cook Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman

maple_tree: refine mas_store_root() on storing NULL

2024-12-14T18:54:13+00:00

commit 0ea120b278ad7f7cfeeb606e150ad04b192df60b upstream. Currently, when storing NULL on mas_store_root(), the behavior could be improved. Storing NULLs over the entire tree may result in a node being used to store a single range. Further stores of NULL may cause the node and tree to be corrupt and cause incorrect behaviour. Fixing the store to the root null fixes the issue by ensuring that a range of 0 - ULONG_MAX results in an empty tree. Users of the tree may experience incorrect values returned if the tree was expanded to store values, then overwritten by all NULLS, then continued to store NULLs over the empty area. For example possible cases are: * store NULL at any range result a new node * store NULL at range [m, n] where m > 0 to a single entry tree result a new node with range [m, n] set to NULL * store NULL at range [m, n] where m > 0 to an empty tree result consecutive NULL slot * it allows for multiple NULL entries by expanding root to store NULLs to an empty tree This patch tries to improve in: * memory efficient by setting to empty tree instead of using a node * remove the possibility of consecutive NULL slot which will prohibit extended null in later operation Link: https://lkml.kernel.org/r/20241031231627.14316-5-richard.weiyang@gmail.com Fixes: 54a611b60590 ("Maple Tree: add new data structure") Signed-off-by: Wei Yang Reviewed-by: Liam R. Howlett Cc: Liam R. Howlett Cc: Sidhartha Kumar Cc: Lorenzo Stoakes Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman

lib: string_helpers: silence snprintf() output truncation warning

2024-12-14T18:54:06+00:00

commit a508ef4b1dcc82227edc594ffae583874dd425d7 upstream. The output of ".%03u" with the unsigned int in range [0, 4294966295] may get truncated if the target buffer is not 12 bytes. This can't really happen here as the 'remainder' variable cannot exceed 999 but the compiler doesn't know it. To make it happy just increase the buffer to where the warning goes away. Fixes: 3c9f3681d0b4 ("[SCSI] lib: add generic helper to print sizes rounded to the correct SI range") Signed-off-by: Bartosz Golaszewski Reviewed-by: Andy Shevchenko Cc: James E.J. Bottomley Cc: Kees Cook Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton Link: https://lore.kernel.org/r/20241101205453.9353-1-brgl@bgdev.pl Signed-off-by: Kees Cook Signed-off-by: Greg Kroah-Hartman

lib/buildid: Fix build ID parsing logic

2024-11-22T14:37:32+00:00

The parse_build_id_buf does not account Elf32_Nhdr header size when getting the build id data pointer and returns wrong build id data as result. This is problem only for stable trees that merged 84887f4c1c3a fix, the upstream build id code was refactored and returns proper build id. Acked-by: Andrii Nakryiko Fixes: 84887f4c1c3a ("lib/buildid: harden build ID parsing logic") Signed-off-by: Jiri Olsa Signed-off-by: Greg Kroah-Hartman

maple_tree: correct tree corruption on spanning store

2024-10-22T13:56:44+00:00

commit bea07fd63192b61209d48cbb81ef474cc3ee4c62 upstream. Patch series "maple_tree: correct tree corruption on spanning store", v3. There has been a nasty yet subtle maple tree corruption bug that appears to have been in existence since the inception of the algorithm. This bug seems far more likely to happen since commit f8d112a4e657 ("mm/mmap: avoid zeroing vma tree in mmap_region()"), which is the point at which reports started to be submitted concerning this bug. We were made definitely aware of the bug thanks to the kind efforts of Bert Karwatzki who helped enormously in my being able to track this down and identify the cause of it. The bug arises when an attempt is made to perform a spanning store across two leaf nodes, where the right leaf node is the rightmost child of the shared parent, AND the store completely consumes the right-mode node. This results in mas_wr_spanning_store() mitakenly duplicating the new and existing entries at the maximum pivot within the range, and thus maple tree corruption. The fix patch corrects this by detecting this scenario and disallowing the mistaken duplicate copy. The fix patch commit message goes into great detail as to how this occurs. This series also includes a test which reliably reproduces the issue, and asserts that the fix works correctly. Bert has kindly tested the fix and confirmed it resolved his issues. Also Mikhail Gavrilov kindly reported what appears to be precisely the same bug, which this fix should also resolve. This patch (of 2): There has been a subtle bug present in the maple tree implementation from its inception. This arises from how stores are performed - when a store occurs, it will overwrite overlapping ranges and adjust the tree as necessary to accommodate this. A range may always ultimately span two leaf nodes. In this instance we walk the two leaf nodes, determine which elements are not overwritten to the left and to the right of the start and end of the ranges respectively and then rebalance the tree to contain these entries and the newly inserted one. This kind of store is dubbed a 'spanning store' and is implemented by mas_wr_spanning_store(). In order to reach this stage, mas_store_gfp() invokes mas_wr_preallocate(), mas_wr_store_type() and mas_wr_walk() in turn to walk the tree and update the object (mas) to traverse to the location where the write should be performed, determining its store type. When a spanning store is required, this function returns false stopping at the parent node which contains the target range, and mas_wr_store_type() marks the mas->store_type as wr_spanning_store to denote this fact. When we go to perform the store in mas_wr_spanning_store(), we first determine the elements AFTER the END of the range we wish to store (that is, to the right of the entry to be inserted) - we do this by walking to the NEXT pivot in the tree (i.e. r_mas.last + 1), starting at the node we have just determined contains the range over which we intend to write. We then turn our attention to the entries to the left of the entry we are inserting, whose state is represented by l_mas, and copy these into a 'big node', which is a special node which contains enough slots to contain two leaf node's worth of data. We then copy the entry we wish to store immediately after this - the copy and the insertion of the new entry is performed by mas_store_b_node(). After this we copy the elements to the right of the end of the range which we are inserting, if we have not exceeded the length of the node (i.e. r_mas.offset <= r_mas.end). Herein lies the bug - under very specific circumstances, this logic can break and corrupt the maple tree. Consider the following tree: Height 0 Root Node / \ pivot = 0xffff / \ pivot = ULONG_MAX / \ 1 A [-----] ... / \ pivot = 0x4fff / \ pivot = 0xffff / \ 2 (LEAVES) B [-----] [-----] C ^--- Last pivot 0xffff. Now imagine we wish to store an entry in the range [0x4000, 0xffff] (note that all ranges expressed in maple tree code are inclusive): 1. mas_store_gfp() descends the tree, finds node A at <=0xffff, then determines that this is a spanning store across nodes B and C. The mas state is set such that the current node from which we traverse further is node A. 2. In mas_wr_spanning_store() we try to find elements to the right of pivot 0xffff by searching for an index of 0x10000: - mas_wr_walk_index() invokes mas_wr_walk_descend() and mas_wr_node_walk() in turn. - mas_wr_node_walk() loops over entries in node A until EITHER it finds an entry whose pivot equals or exceeds 0x10000 OR it reaches the final entry. - Since no entry has a pivot equal to or exceeding 0x10000, pivot 0xffff is selected, leading to node C. - mas_wr_walk_traverse() resets the mas state to traverse node C. We loop around and invoke mas_wr_walk_descend() and mas_wr_node_walk() in turn once again. - Again, we reach the last entry in node C, which has a pivot of 0xffff. 3. We then copy the elements to the left of 0x4000 in node B to the big node via mas_store_b_node(), and insert the new [0x4000, 0xffff] entry too. 4. We determine whether we have any entries to copy from the right of the end of the range via - and with r_mas set up at the entry at pivot 0xffff, r_mas.offset <= r_mas.end, and then we DUPLICATE the entry at pivot 0xffff. 5. BUG! The maple tree is corrupted with a duplicate entry. This requires a very specific set of circumstances - we must be spanning the last element in a leaf node, which is the last element in the parent node. spanning store across two leaf nodes with a range that ends at that shared pivot. A potential solution to this problem would simply be to reset the walk each time we traverse r_mas, however given the rarity of this situation it seems that would be rather inefficient. Instead, this patch detects if the right hand node is populated, i.e. has anything we need to copy. We do so by only copying elements from the right of the entry being inserted when the maximum value present exceeds the last, rather than basing this on offset position. The patch also updates some comments and eliminates the unused bool return value in mas_wr_walk_index(). The work performed in commit f8d112a4e657 ("mm/mmap: avoid zeroing vma tree in mmap_region()") seems to have made the probability of this event much more likely, which is the point at which reports started to be submitted concerning this bug. The motivation for this change arose from Bert Karwatzki's report of encountering mm instability after the release of kernel v6.12-rc1 which, after the use of CONFIG_DEBUG_VM_MAPLE_TREE and similar configuration options, was identified as maple tree corruption. After Bert very generously provided his time and ability to reproduce this event consistently, I was able to finally identify that the issue discussed in this commit message was occurring for him. Link: https://lkml.kernel.org/r/cover.1728314402.git.lorenzo.stoakes@oracle.com Link: https://lkml.kernel.org/r/48b349a2a0f7c76e18772712d0997a5e12ab0a3b.1728314403.git.lorenzo.stoakes@oracle.com Fixes: 54a611b60590 ("Maple Tree: add new data structure") Signed-off-by: Lorenzo Stoakes Reported-by: Bert Karwatzki Closes: https://lore.kernel.org/all/20241001023402.3374-1-spasswolf@web.de/ Tested-by: Bert Karwatzki Reported-by: Mikhail Gavrilov Closes: https://lore.kernel.org/all/CABXGCsOPwuoNOqSMmAvWO2Fz4TEmPnjFj-b7iF+XFRu1h7-+Dg@mail.gmail.com/ Acked-by: Vlastimil Babka Reviewed-by: Liam R. Howlett Tested-by: Mikhail Gavrilov Reviewed-by: Wei Yang Cc: Matthew Wilcox Cc: Sidhartha Kumar Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman

bootconfig: Fix the kerneldoc of _xbc_exit()

2024-10-17T13:22:10+00:00

[ Upstream commit 298b871cd55a607037ac8af0011b9fdeb54c1e65 ] Fix the kerneldoc of _xbc_exit() which is updated to have an @early argument and the function name is changed. Link: https://lore.kernel.org/all/171321744474.599864.13532445969528690358.stgit@devnote2/ Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-kbuild-all/202404150036.kPJ3HEFA-lkp@intel.com/ Fixes: 89f9a1e876b5 ("bootconfig: use memblock_free_late to free xbc memory to buddy") Signed-off-by: Masami Hiramatsu (Google) Signed-off-by: Sasha Levin

lib/buildid: harden build ID parsing logic

2024-10-17T13:22:06+00:00

[ Upstream commit 905415ff3ffb1d7e5afa62bacabd79776bd24606 ] Harden build ID parsing logic, adding explicit READ_ONCE() where it's important to have a consistent value read and validated just once. Also, as pointed out by Andi Kleen, we need to make sure that entire ELF note is within a page bounds, so move the overflow check up and add an extra note_size boundaries validation. Fixes tag below points to the code that moved this code into lib/buildid.c, and then subsequently was used in perf subsystem, making this code exposed to perf_event_open() users in v5.12+. Cc: stable@vger.kernel.org Reviewed-by: Eduard Zingerman Reviewed-by: Jann Horn Suggested-by: Andi Kleen Fixes: bd7525dacd7e ("bpf: Move stack_map_get_build_id into lib") Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20240829174232.3133883-2-andrii@kernel.org Signed-off-by: Alexei Starovoitov Signed-off-by: Sasha Levin

build-id: require program headers to be right after ELF header

2024-10-17T13:22:05+00:00

[ Upstream commit 961a2851324561caed579764ffbee3db82b32829 ] Neither ELF spec not ELF loader require program header to be placed right after ELF header, but build-id code very much assumes such placement: See find_get_page(vma->vm_file->f_mapping, 0); line and checks against PAGE_SIZE. Returns errors for now until someone rewrites build-id parser to be more inline with load_elf_binary(). Link: https://lkml.kernel.org/r/d58bc281-6ca7-467a-9a64-40fa214bd63e@p183 Signed-off-by: Alexey Dobriyan Reviewed-by: Jiri Olsa Signed-off-by: Andrew Morton Stable-dep-of: 905415ff3ffb ("lib/buildid: harden build ID parsing logic") Signed-off-by: Sasha Levin

mm/filemap: optimize filemap folio adding

2024-10-17T13:21:26+00:00

commit 6758c1128ceb45d1a35298912b974eb4895b7dd9 upstream. Instead of doing multiple tree walks, do one optimism range check with lock hold, and exit if raced with another insertion. If a shadow exists, check it with a new xas_get_order helper before releasing the lock to avoid redundant tree walks for getting its order. Drop the lock and do the allocation only if a split is needed. In the best case, it only need to walk the tree once. If it needs to alloc and split, 3 walks are issued (One for first ranged conflict check and order retrieving, one for the second check after allocation, one for the insert after split). Testing with 4K pages, in an 8G cgroup, with 16G brd as block device: echo 3 > /proc/sys/vm/drop_caches fio -name=cached --numjobs=16 --filename=/mnt/test.img \ --buffered=1 --ioengine=mmap --rw=randread --time_based \ --ramp_time=30s --runtime=5m --group_reporting Before: bw ( MiB/s): min= 1027, max= 3520, per=100.00%, avg=2445.02, stdev=18.90, samples=8691 iops : min=263001, max=901288, avg=625924.36, stdev=4837.28, samples=8691 After (+7.3%): bw ( MiB/s): min= 493, max= 3947, per=100.00%, avg=2625.56, stdev=25.74, samples=8651 iops : min=126454, max=1010681, avg=672142.61, stdev=6590.48, samples=8651 Test result with THP (do a THP randread then switch to 4K page in hope it issues a lot of splitting): echo 3 > /proc/sys/vm/drop_caches fio -name=cached --numjobs=16 --filename=/mnt/test.img \ --buffered=1 --ioengine=mmap -thp=1 --readonly \ --rw=randread --time_based --ramp_time=30s --runtime=10m \ --group_reporting fio -name=cached --numjobs=16 --filename=/mnt/test.img \ --buffered=1 --ioengine=mmap \ --rw=randread --time_based --runtime=5s --group_reporting Before: bw ( KiB/s): min= 4141, max=14202, per=100.00%, avg=7935.51, stdev=96.85, samples=18976 iops : min= 1029, max= 3548, avg=1979.52, stdev=24.23, samples=18976· READ: bw=4545B/s (4545B/s), 4545B/s-4545B/s (4545B/s-4545B/s), io=64.0KiB (65.5kB), run=14419-14419msec After (+12.5%): bw ( KiB/s): min= 4611, max=15370, per=100.00%, avg=8928.74, stdev=105.17, samples=19146 iops : min= 1151, max= 3842, avg=2231.27, stdev=26.29, samples=19146 READ: bw=4635B/s (4635B/s), 4635B/s-4635B/s (4635B/s-4635B/s), io=64.0KiB (65.5kB), run=14137-14137msec The performance is better for both 4K (+7.5%) and THP (+12.5%) cached read. Link: https://lkml.kernel.org/r/20240415171857.19244-5-ryncsn@gmail.com Signed-off-by: Kairui Song Cc: Matthew Wilcox (Oracle) Signed-off-by: Andrew Morton Closes: https://lore.kernel.org/linux-mm/A5A976CB-DB57-4513-A700-656580488AB6@flyingcircus.io/ [ kasong@tencent.com: minor adjustment of variable declarations ] Signed-off-by: Greg Kroah-Hartman

lib/xarray: introduce a new helper xas_get_order

2024-10-17T13:21:26+00:00

commit a4864671ca0bf51c8e78242951741df52c06766f upstream. It can be used after xas_load to check the order of loaded entries. Compared to xa_get_order, it saves an XA_STATE and avoid a rewalk. Added new test for xas_get_order, to make the test work, we have to export xas_get_order with EXPORT_SYMBOL_GPL. Also fix a sparse warning by checking the slot value with xa_entry instead of accessing it directly, as suggested by Matthew Wilcox. [kasong@tencent.com: simplify comment, sparse warning fix, per Matthew Wilcox] Link: https://lkml.kernel.org/r/20240416071722.45997-4-ryncsn@gmail.com Link: https://lkml.kernel.org/r/20240415171857.19244-4-ryncsn@gmail.com Signed-off-by: Kairui Song Cc: Matthew Wilcox (Oracle) Signed-off-by: Andrew Morton Stable-dep-of: 6758c1128ceb ("mm/filemap: optimize filemap folio adding") Signed-off-by: Greg Kroah-Hartman