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Peter Anvin" , Mathieu Desnoyers , Kees Cook , Sam James Cc: Jens Remus , bpf@vger.kernel.org, linux-mm@kvack.org, Namhyung Kim , Andrii Nakryiko , "Jose E. Marchesi" , Beau Belgrave , Florian Weimer , "Carlos O'Donell" , Masami Hiramatsu , Jiri Olsa , Arnaldo Carvalho de Melo , Andrew Morton , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Heiko Carstens , Vasily Gorbik , Ilya Leoshkevich , "Steven Rostedt (Google)" Subject: [PATCH v16 12/20] unwind_user/sframe: Add .sframe validation option Date: Thu, 21 May 2026 16:25:38 +0200 Message-ID: <20260521142546.3908498-13-jremus@linux.ibm.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260521142546.3908498-1-jremus@linux.ibm.com> References: <20260521142546.3908498-1-jremus@linux.ibm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNTIxMDE0MiBTYWx0ZWRfX75JMwD44D9po Tc2RJGNzA99v0U34GDmAJZcsfdGsiEbNz28O6pUZx4vtcRt6344OlxoXzCtSJ9bIZdlVgyDD4to c9rV6vBbT+cqsHTY9/vgTmryhGeZ0Vd1SdKqSPAdHX0AEvVaMzhO28w581fS771GtdaRlNd27FO xGr+hY2oMYn9ju5VMf7ZmYRI3XlQXUCFVe+9D5n+Vnj+9lgHV388nRVqs7uTo4UKLNnoYJXJs4a j6eoeP/s5u1U0AtLegph1nlAjjq9aFnNz+YHRuryRLw/VwF0SfRKdJpgiVUionX1uEjIMGkehvF D06F5G13u6UJ+LsvjBcpjcFwpTEPMx7ziYP602PI0+REPIYKeNflVrN8oysnXZUcv9Us0MJPbix zT7CBmXsz4Xi5oW/G+SZ7nvSPSEYg8PMNxAUdXIs6Dy2FnkjrFFxmI1lcjlI1VToOYIS36yqTb1 KNYgYFDCotEXo+YPTWQ== X-Authority-Analysis: v=2.4 cv=BNuDalQG c=1 sm=1 tr=0 ts=6a0f15f7 cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=NGcC8JguVDcA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=iQ6ETzBq9ecOQQE5vZCe:22 a=VwQbUJbxAAAA:8 a=meVymXHHAAAA:8 a=pGLkceISAAAA:8 a=VnNF1IyMAAAA:8 a=RXKZOtKmAAAA:8 a=iNKnMr3YqTL5pEm6fAYA:9 a=2JgSa4NbpEOStq-L5dxp:22 a=UFF3uGjEBZWolfm0k6KQ:22 X-Proofpoint-ORIG-GUID: sacPi_ffize2HNJD9Ulb5EI3vTRjMch- X-Proofpoint-GUID: 2kWA44K5Xjeos5_bgX_8kSIVrC6qCLZb X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-05-21_02,2026-05-18_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 adultscore=0 priorityscore=1501 malwarescore=0 impostorscore=0 suspectscore=0 lowpriorityscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2605130000 definitions=main-2605210142 X-Rspam-User: X-Rspamd-Queue-Id: 39F3D180008 X-Rspamd-Server: rspam03 X-Stat-Signature: qqjthm6ou86suw45qgpqew4h6tkyj7ds X-HE-Tag: 1779373577-146507 X-HE-Meta: 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 9rcqZ8Er 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: From: Josh Poimboeuf Add a debug feature to validate all .sframe sections when first loading the file rather than on demand. [ Jens Remus: Add support for SFrame V3. Add support for PC-relative FDE function start offset. Adjust to rename of struct sframe_fre to sframe_fre_internal. Use %#x/%#lx format specifiers. ] Signed-off-by: Josh Poimboeuf Signed-off-by: Steven Rostedt (Google) Reviewed-by: Indu Bhagat Signed-off-by: Jens Remus --- Notes (jremus): Changes in v16: - sframe_validate_section(): Allow for a FDE[0] function start address of zero. (Sashiko AI) - sframe_validate_section(): Replace alternation between two FREs with simpler logic used for FDE and use a prev_ip_off. Changes in v15: - sframe_validate_section(): Fix format specifier for number of FREs in debug message. (Sashiko AI) - Normalize error code usage (.sframe is removed for all but ENOENT): ENOENT: No sframe or no FDE for IP found (FDE found but no FRE is EINVAL) EFAULT: Bad address EINVAL: Invalid input or sframe Changes in v14: - Add debug message if safe_read_fde() fails. - Update function names in debug messages. - Uppercase terms FDE and FRE in debug messages. Changes in v13: - Update to SFrame V3: - Print struct sframe_fde_internal fields fda_off and info2 in debug message. - Adjust to rename of struct sframe_fde_internal field func_start_addr to func_addr. - Use format strings "%#x" and "%#lx" instead of "0x%x" and "0x%lx". - Reword commit message (my changes). arch/Kconfig | 19 +++++++++ kernel/unwind/sframe.c | 92 ++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 111 insertions(+) diff --git a/arch/Kconfig b/arch/Kconfig index 37549832bd1f..132249d342a3 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -490,6 +490,25 @@ config HAVE_UNWIND_USER_SFRAME bool select UNWIND_USER +config SFRAME_VALIDATION + bool "Enable .sframe section debugging" + depends on HAVE_UNWIND_USER_SFRAME + depends on DYNAMIC_DEBUG + help + When adding an .sframe section for a task, validate the entire + section immediately rather than on demand. + + This is a debug feature which is helpful for rooting out .sframe + section issues. If the .sframe section is corrupt, it will fail to + load immediately, with more information provided in dynamic printks. + + This has a significant page cache footprint due to its reading of the + entire .sframe section for every loaded executable and shared + library. Also, it's done for all processes, even those which don't + get stack traced by the kernel. Not recommended for general use. + + If unsure, say N. + config HAVE_PERF_REGS bool help diff --git a/kernel/unwind/sframe.c b/kernel/unwind/sframe.c index 2cfa274cd8dc..e6d66ae8e7ac 100644 --- a/kernel/unwind/sframe.c +++ b/kernel/unwind/sframe.c @@ -384,6 +384,94 @@ int sframe_find(unsigned long ip, struct unwind_user_frame *frame) goto end; } +#ifdef CONFIG_SFRAME_VALIDATION + +static int safe_read_fde(struct sframe_section *sec, + unsigned int fde_num, struct sframe_fde_internal *fde) +{ + int ret; + + if (!user_read_access_begin((void __user *)sec->sframe_start, + sec->sframe_end - sec->sframe_start)) + return -EFAULT; + ret = __read_fde(sec, fde_num, fde); + user_read_access_end(); + return ret; +} + +static int safe_read_fre(struct sframe_section *sec, + struct sframe_fde_internal *fde, + unsigned long fre_addr, + struct sframe_fre_internal *fre) +{ + int ret; + + if (!user_read_access_begin((void __user *)sec->sframe_start, + sec->sframe_end - sec->sframe_start)) + return -EFAULT; + ret = __read_fre(sec, fde, fre_addr, fre); + user_read_access_end(); + return ret; +} + +static int sframe_validate_section(struct sframe_section *sec) +{ + struct sframe_fde_internal fde; + unsigned long prev_func_addr; + unsigned int i; + + for (i = 0; i < sec->num_fdes; i++) { + struct sframe_fre_internal fre; + unsigned long fre_addr; + u32 prev_ip_off; + unsigned int j; + int ret; + + ret = safe_read_fde(sec, i, &fde); + if (ret) { + dbg_sec("safe_read_fde(%u) failed\n", i); + return ret; + } + + if (i && fde.func_addr <= prev_func_addr) { + dbg_sec("FDE %u not sorted\n", i); + return -EINVAL; + } + prev_func_addr = fde.func_addr; + + fre_addr = sec->fres_start + fde.fres_off; + for (j = 0; j < fde.fres_num; j++) { + ret = safe_read_fre(sec, &fde, fre_addr, &fre); + if (ret) { + dbg_sec("FDE %u: safe_read_fre(%u) failed\n", i, j); + dbg_sec("FDE: func_addr:%#lx func_size:%#x fda_off:%#x fres_off:%#x fres_num:%u info:%u info2:%u rep_size:%u\n", + fde.func_addr, fde.func_size, + fde.fda_off, + fde.fres_off, fde.fres_num, + fde.info, fde.info2, + fde.rep_size); + return ret; + } + + if (j && fre.ip_off <= prev_ip_off) { + dbg_sec("FDE %u: FRE %u not sorted\n", i, j); + return -EINVAL; + } + prev_ip_off = fre.ip_off; + + fre_addr += fre.size; + } + } + + return 0; +} + +#else /* !CONFIG_SFRAME_VALIDATION */ + +static int sframe_validate_section(struct sframe_section *sec) { return 0; } + +#endif /* !CONFIG_SFRAME_VALIDATION */ + static void free_section(struct sframe_section *sec) { dbg_free(sec); @@ -502,6 +590,10 @@ int sframe_add_section(unsigned long sframe_start, unsigned long sframe_end, goto err_free; } + ret = sframe_validate_section(sec); + if (ret) + goto err_free; + ret = mtree_insert_range(sframe_mt, sec->text_start, sec->text_end - 1, sec, GFP_KERNEL_ACCOUNT); if (ret) { -- 2.51.0